1,126 results on '"Wai Yeung Wong"'
Search Results
152. A Pure Blue Phosphorescent Organic Light‐Emitting Diode with an External Quantum Efficiency of Over 30% by Using a Tandem Device Architecture
- Author
-
Zhao Chen, Naifan Tian, Peng Tao, Shuming Chen, Dongge Ma, Lixiang Wang, and Wai‐Yeung Wong
- Subjects
Mechanics of Materials ,Mechanical Engineering - Published
- 2022
153. Fluorescence Imaging and Photodynamic Inactivation of Bacteria Based on Cationic Cyclometalated Iridium(III) Complexes with Aggregation-Induced Emission Properties
- Author
-
Guo-Gang Shan, Wai Yeung Wong, Chuen Kam, Po-Yu Ho, Sin-Ying Lee, Yuning Hong, Sijie Chen, and Junfei Zhu
- Subjects
Denticity ,medicine.medical_treatment ,Optical Imaging ,Biomedical Engineering ,Rational design ,Cationic polymerization ,Pharmaceutical Science ,chemistry.chemical_element ,Photodynamic therapy ,Photochemistry ,Gram-Positive Bacteria ,Iridium ,Fluorescence ,Anti-Bacterial Agents ,Biomaterials ,chemistry ,Gram-Negative Bacteria ,medicine ,Structural isomer ,Molecule - Abstract
Antibacterial photodynamic therapy (PDT) is one of the emerging methods for curbing multidrug-resistant bacterial infections. Effective fluorescent photosensitizers with dual functions of bacteria imaging and PDT applications are highly desirable. In this study, three cationic and heteroleptic cyclometalated Ir(III) complexes with the formula of [Ir(CˆN)2 (NˆN)][PF6 ] are prepared and characterized. These Ir(III) complexes named Ir(ppy)2 bP, Ir(1-pq)2 bP, and Ir(2-pq)2 bP are comprised of three CˆN ligands (i.e., 2-phenylpyridine (ppy), 1-phenylisoquinoline (1-pq), and 2-phenylquinoline (2-pq)) and one NˆN bidentate co-ligand (bP). The photophysical characterizations demonstrate that these Ir(III) complexes are red-emitting, aggregation-induced emission active luminogens. The substitution of phenylpyridine with phenylquinoline isomers in the molecules greatly enhances their UV and visible-light absorbance as well as the photoinduced reactive oxygen species (ROS) generation ability. All three Ir(III) complexes can stain both Gram-positive and Gram-negative bacteria efficiently. Interestingly, even though Ir(1-pq)2 bP and Ir(2-pq)2 bP are constitutional isomers with very similar structures and similar ROS generation ability in buffer, the former eradicates bacteria much more effectively than the other through white light-irradiated photodynamic inactivation. This work will provide valuable information on the rational design of Ir(III) complexes for fluorescence imaging and efficient photodynamic inactivation of bacteria.
- Published
- 2021
154. Synthesis, characterization, and optoelectronic properties of phenothiazine-based organic co-poly-ynes
- Author
-
Abdul Munam, Paul R. Raithby, Yingying Fu, Idris Juma Al-Busaidi, Jonathan M. Skelton, Shuming Chen, Muhammad S. Khan, Wai Yeung Wong, Youming Zhang, Rayya A. Al-Balushi, Zhiyuan Xie, Ashanul Haque, Jahangir Ahmad Rather, Rashid Ilmi, and Shahidul M. Islam
- Subjects
Chemistry(all) ,Sonogashira coupling ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,Polymer solar cell ,Rhodamine 6G ,chemistry.chemical_compound ,Phenothiazine ,Materials Chemistry ,Absorption (electromagnetic radiation) ,chemistry.chemical_classification ,Chemistry ,business.industry ,General Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Characterization (materials science) ,Optoelectronics ,0210 nano-technology ,business - Abstract
We present the synthesis and characterization of seven new organic co-poly-ynes P1-P7 incorporating the phenothiazine (PTZ) motif and evaluate their optoelectronic properties and performance in polymer light-emitting diodes and polymer solar cells (PLEDs/PSCs). The co-poly-ynes were obtained in moderate to high yields via Sonogashira coupling reactions and characterized using analytical, spectroscopic and electrochemical techniques and complementary quantum-chemical modelling. The materials show strong optical absorption in the visible region of the spectrum and most also show strong emission with quantum yields in the range of 13-41% relative to rhodamine 6G (R6G). PLED devices based on the co-poly-ynes were prepared and the most promising was measured to have a brightness of up to 1.10 × 104 cd m-2. PSCs based on donor materials incorporating some of the polymers were prepared and demonstrated power conversion efficiencies of up to 0.24%. This journal is
- Published
- 2021
155. A simple and efficient approach toward deep-red to near-infrared-emitting iridium(iii) complexes for organic light-emitting diodes with external quantum efficiencies of over 10
- Author
-
Wai Yeung Wong, Dawei Wen, Hongyang Zhang, Qingguang Zeng, Zhao Chen, Wenhai Wu, and Shuming Chen
- Subjects
Materials science ,business.industry ,Doping ,Near-infrared spectroscopy ,chemistry.chemical_element ,Phosphor ,General Chemistry ,Chemistry ,chemistry ,OLED ,Optoelectronics ,Quantum efficiency ,Iridium ,Phosphorescence ,business ,Diode - Abstract
While the external quantum efficiency (EQE) of iridium(iii) (Ir(iii)) phosphor based near-infrared organic light-emitting diodes (NIR OLEDs) has been limited to 5.7% to date, there is no significant EQE improvement for these types of OLEDs due to the lack of efficient Ir(iii) emitters. Here, a convenient approach within three synthetic steps is developed to afford two novel and efficient deep-red to near-infrared (DR-NIR) emitting phosphors (CNIr and TCNIr), in which a cyano group is added into a commercial red emitter named Ir(piq)2(acac) to significantly stabilize the lowest unoccupied molecular orbitals of the newly designed Ir(iii) complexes. They emit strong DR-NIR phosphorescence emissions at a wavelength of around 700 nm, with relatively high absolute quantum efficiencies of around 45% for their doped films. DR-NIR OLEDs made using CNIr and TCNIr exhibit high-efficiencies, affording peak EQEs of 10.62% and 9.59% with emission peak wavelengths of 690 and 706 nm, respectively. All these devices represent the most efficient Ir(iii)-based DR-NIR OLEDs with a similar color gamut. The simplified synthesis procedure of the DR-NIR-emitting phosphors in conjunction with their excellent performance in OLEDs confirms our efficient strategy to achieve the DR-NIR-emitting Ir(iii) phosphors., The simplest and the most efficient deep-red to near-infrared-emitting emitters afford a new record external quantum efficiency for iridium(iii) complex based deep-red to near-infrared organic light-emitting diodes.
- Published
- 2021
156. Supercapacitor electrodes based on metal‐organic compounds from the first transition metal series
- Author
-
Zhiyuan Xie, Bulin Chen, Wai Yeung Wong, and Linli Xu
- Subjects
Supercapacitor ,Materials science ,supercapacitors ,Series (mathematics) ,first transition metal series ,TJ807-830 ,Electrochemistry ,Renewable energy sources ,Metal ,Environmental sciences ,metal‐organic compounds ,Transition metal ,Chemical engineering ,electrochemistry ,metal‐organic frameworks ,visual_art ,Electrode ,visual_art.visual_art_medium ,Metal-organic framework ,GE1-350 - Abstract
Metal‐organic compounds, including molecular complexes and coordination polymers, have attracted much attention as electrode materials in supercapacitors owing to their large surface area, high porosity, tailorable pore size, controllable structure, good electrochemical reversibility, and abundant active sites. Among the variety of metal‐organic compounds exhibiting desired supercapacitor performances (high specific capacitance, long cycling life, high energy density, and power density), those with metals in the first transition metal series are the most studied due to their rich covalent states, light atom weight, environmental‐friendliness, non‐toxicity, and low cost. In this review, the recent reports on the metal‐organic compounds of the first transition metal series as electrode materials in supercapacitors are summarized and their electrode and device performances are discussed in terms of different metal elements and typical multidentate ligands. Moreover, the current challenges, design strategies, future opportunities and further research directions are also highlighted for metal‐organic compounds in the field of supercapacitors.
- Published
- 2021
157. Synthesis and Characterization of a Large-Sized π-Conjugated Copper(II) Complex Nanosheet
- Author
-
Zhiyuan Xie, Wai Yeung Wong, and Yurong Liu
- Subjects
Materials science ,Polymers and Plastics ,Ligand ,Scanning electron microscope ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Homogeneous distribution ,Copper ,0104 chemical sciences ,X-ray photoelectron spectroscopy ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Materials Chemistry ,0210 nano-technology ,Spectroscopy ,Nanosheet - Abstract
Inspired by the flexibility of the bottom-up approach in choosing building blocks of two-dimensional (2D) materials, a π-conjugated metal complex nanosheet (HHTP-Cu) was successfully prepared by the coordination of the ligand 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and Cu(II) ion at the water/oil interface. Field-emission scanning electron microscopy disclosed the large-size domain and transmission electron microscopy revealed the sheet morphology of the nanosheet. The flat and smooth surface was also confirmed by atomic force microscopy which further demonstrated the proposed structure. Energy dispersive X-ray spectroscopy was applied to verify the homogeneous distribution of the elements while X-ray photoelectron spectroscopy was used to investigate the composition of the nanosheet.
- Published
- 2019
158. A Sublimable Dinuclear Cuprous Complex Showing Selective Luminescence Vapochromism in the Crystalline State
- Author
-
Wai Yeung Wong, Xing-Wei Chen, Guijiang Zhou, Hua-Li Yuan, Jing-Lin Chen, Li-Hua He, Jin-Yun Wang, Sui-Jun Liu, and He-Rui Wen
- Subjects
Inorganic Chemistry ,Crystallography ,010405 organic chemistry ,Chemistry ,Physical and Theoretical Chemistry ,010402 general chemistry ,Luminescence ,01 natural sciences ,0104 chemical sciences - Abstract
A new sublimable dicopper(I) complex bearing 1,2-bis(diphenylphosphino)ethane and 5-trifluoromethyl-3-(2'-pyridyl)pyrazolate ligands has been designed and synthesized, and its crystalline solvated and nonsolvated compounds have also been obtained and investigated. It is shown that only the crystalline solvated compound exhibits reversible and selective luminescence vapochromism, arising from its unique "pyridyl/CH
- Published
- 2019
159. Synthesis and characterization of platinum(II) polymetallaynes functionalized with phenoxazine-based spacer. A comparison with the phenothiazine congener
- Author
-
Wai Yeung Wong, Li Li, and Lei Wang
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,Organic Chemistry ,chemistry.chemical_element ,Polymer ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Phenothiazine ,Polymer chemistry ,Materials Chemistry ,Thiophene ,Singlet state ,Physical and Theoretical Chemistry ,Platinum ,Phenoxazine - Abstract
A new series of soluble, solution-processable metallopolyynes of platinum(II) functionalized with electron-rich phenoxazine–oligothiophene rings and their corresponding dinuclear model complexes were synthesized and characterized. The influence of the inclusion of thienyl rings along the polymer chain on the optical, electronic and photovoltaic properties of these metallopolymers was studied. The evolution of the singlet and triplet excited states in these metal-based materials was elucidated in detail. It is shown that addition of the thiophene rings can elevate the HOMO energy level of the polymers. The absorption edge of the oxygen analogue is more red-shifted than that of the sulfur congener, which is attributed to the stronger electron-donating ability of the phenoxazine unit than that of the phenothiazine group. The down-shifted HOMO level of the phenothiazine-based polymer is found to enhance the photovoltaic performance by increasing the open-circuit voltage of the polymer solar cell relative to the phenoxazine-based congener. At the same donor:acceptor blend ratio of 1:4, the light-harvesting capability and solar cell efficiency notably increase as the thienyl rings are added.
- Published
- 2019
160. Solvent‐Induced Cluster‐to‐Cluster Transformation of Homoleptic Gold(I) Thiolates between Catenane and Ring‐in‐Ring Structures
- Author
-
Jie-Sheng Huang, Liangliang Wu, Wai Yeung Wong, Tim Wai Hung Ang, Xiao Yong Chang, Guang Tao Xu, and Chi-Ming Che
- Subjects
Alkane ,chemistry.chemical_classification ,010405 organic chemistry ,Catenane ,Supramolecular chemistry ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Hexane ,Solvent ,chemistry.chemical_compound ,Crystallography ,chemistry ,Proton NMR ,Density functional theory ,Homoleptic - Abstract
Supramolecular ensembles adopting ring-in-ring structures are less developed compared with catenanes featuring interlocked rings. While catenanes with inter-ring closed-shell metallophilic interactions, such as d10 -d10 AuI -AuI interactions, have been well-documented, the ring-in-ring complexes featuring such metallophilic interactions remain underdeveloped. Herein is described an unprecedented ring-in-ring structure of a AuI -thiolate Au12 cluster formed by recrystallization of a AuI -thiolate Au10 [2]catenane from alkane solvents such as hexane, with use of a bulky dibutylfluorene-2-thiolate ligand. The ring-in-ring AuI -thiolate Au12 cluster features inter-ring AuI -AuI interactions and underwent cluster core change to form the thermodynamically more stable Au10 [2]catenane structure upon dissolving in, or recrystallization from, other solvents such as CH2 Cl2 , CHCl3 , and CH2 Cl2 /MeCN. The cluster-to-cluster transformation process was monitored by 1 H NMR and ESI-MS measurements. Density functional theory (DFT) calculations were performed to provide insight into the mechanism of the "ring-in-ring⇌ [2]catenane" interconversions.
- Published
- 2019
161. Amphiphilic bimetallic polymer as single-source precursors for the one-pot synthesis of L10-phase FePt nanoparticles
- Author
-
Zhuoxun Wei, Kuo Fu, Lei Lv, Zhengong Meng, Wai Yeung Wong, and Zhen Qiang Yu
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,Organic Chemistry ,Dispersity ,Nanoparticle ,Polymer ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Inorganic Chemistry ,Crystallinity ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Amphiphile ,Materials Chemistry ,Self-assembly ,Physical and Theoretical Chemistry ,Bimetallic strip ,Ethylene glycol - Abstract
Amphiphilic polymers have attracted extensive research attention in constructing various nanostructures by self-assembly. Here we designed and synthesized two amphiphilic bimetallic polymers with different length of the tails P1 and P2, in which Fe,Pt-containing conjugated complex acted as the hydrophobic block and hydrophilic poly(ethylene glycol) (PEG) was bonded to the bimetallic core as the flexible tails. P1 and P2 were used as the single-source precursors to prepare FePt nanoparticles (NPs) by one-pot pyrolysis. The resultant NPs were fully characterized and had a chemically ordered face-centered tetragonal (fct) phase with high crystallinity. The size of NPs pyrolyzed from P1 and P2 was 24.7 and 8.2 nm with the relative coercivity of 9.6 and 1.3 kOe, respectively. The difference was preliminarily explained by the discrepancy of their degrees of crystallinity, and also analyzed by the precursors’ structural effect. The amphiphilic design showed a good potential in preparing monodisperse ferromagnetic FePt NPs, and the possible favorable properties of self-assembly might provide a bright venue for future magnetic recording media.
- Published
- 2019
162. Synthesis, characterization and photovoltaic properties of platinum-containing poly(aryleneethynylene) polymers with electron-deficient diketopyrrolopyrrole unit
- Author
-
Qian Liu, Wai Yeung Wong, Shu Kong So, and Hongmei Zhan
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,business.industry ,Organic Chemistry ,chemistry.chemical_element ,Polymer ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Biochemistry ,Coupling reaction ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Photovoltaics ,Polymer chemistry ,Materials Chemistry ,Thiophene ,Moiety ,Thermal stability ,Physical and Theoretical Chemistry ,Platinum ,business - Abstract
Three new solution-processable Pt(II)-containing poly(aryleneethynylene) polymers based on diketopyrrolopyrrole moiety and their corresponding diplatinum model complexes were synthesized via the Sonogashira-type coupling reaction of the platinum(II) chloride precursor and each of the diethynyl ligands. The photophysical, thermal stability, electrochemical, carrier mobility and photovoltaic properties of these polymers were fully investigated. These polymers exhibit strong absorption bands in the range of 550–750 nm, and fluorescent bands between 650 and 850 nm. One thiophene flanked diketopyrrolopyrrole based polymer with linear n-octyl chains shows a better photovoltaic performance than that made from the branched 2-ethylhexyl analogue.
- Published
- 2019
163. Inkjet printed pseudocapacitive electrodes on laser-induced graphene for electrochemical energy storage
- Author
-
Feng Yan, Wai Yeung Wong, Cheuk Lam Ho, Zhengong Meng, Guijun Li, Shu Ping Lau, and Jiasheng Qian
- Subjects
Supercapacitor ,Materials science ,Renewable Energy, Sustainability and the Environment ,Graphene ,Materials Science (miscellaneous) ,Coffee ring effect ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,Substrate (printing) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Capacitance ,Pseudocapacitance ,0104 chemical sciences ,law.invention ,Fuel Technology ,Nuclear Energy and Engineering ,chemistry ,law ,Electrode ,0210 nano-technology ,Cobalt - Abstract
Pseudocapacitance boosts the capacitance of supercapacitors by introducing additional redox sites with fast faradaic reactions. Here, we demonstrate the preparation of pseudocapacitive electrodes by inkjet printing bis-terpyridyl based molecular cobalt complexes as pseudocapacitive additives on laser induced graphene films. The substrate temperature during inkjet printing can effectively tune the morphology of the pseudocapacitive additives by overcoming the influence of coffee ring effect. Under optimum conditions, the capacitance of the pseudocapacitive electrodes was enhanced for 75 times over pristine graphene films. This approach can also be employed for the deposition of other functional materials via inkjet printing.
- Published
- 2019
164. Nanostructured Bimetallic Block Copolymers as Precursors to Magnetic FePt Nanoparticles
- Author
-
Ian Manners, Guijun Li, Cheuk Lam Ho, Wai Yeung Wong, Zhengong Meng, Sze Chun Yiu, George R. Whittell, Jessica Gwyther, Jenner Ho Loong Ngai, and Adam Nunns
- Subjects
Diffraction ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Block (periodic table) ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Chemical engineering ,Transmission electron microscopy ,Materials Chemistry ,Copolymer ,0210 nano-technology ,Spectroscopy ,Pyrolysis ,Bimetallic strip - Abstract
Phase-separated block copolymers (BCPs) that function as precursors to arrays of FePt nanoparticles (NPs) are of potential interest for the creation of media for the next-generation high-density magnetic data storage devices. A series of bimetallic BCPs has been synthesized by incorporating a complex containing Fe and Pt centers into the coordinating block of four different poly(styrene-b-4-vinylpyridine)s (PS-b-P4VPs, P1-P4). To facilitate phase separation for the resulting metalated BCPs (PM1-PM4), a loading of the FePt-bimetallic complex corresponding to ca. 20% was used. The bulk and thin-film self-assembly of these BCPs was studied by transmission electron microscopy (TEM) and atomic force microscopy, respectively. The spherical and cylindrical morphologies observed for the metalated BCPs corresponded to those observed for the metal-free BCPs. The products from the pyrolysis of the BCPs in bulk were also characterized by TEM, powder X-ray diffraction, and energy-dispersive X-ray spectroscopy, which indicated that the FePt NPs formed exist in an fct phase with average particle sizes of ca. 4-8 nm within a carbonaceous matrix. A comparison of the pyrolysis behavior of the metalated BCP (PM3), the metalated P4VP homopolymer (PM5), and the molecular model organometallic complex revealed the importance of using a nanostructured BCP approach for the synthesis of ferromagnetic FePt NPs with a smaller average NP size and a close to 1:1 Fe/Pt stoichiometric ratio.
- Published
- 2019
165. Excitation Wavelength Dependent Fluorescence of an ESIPT Triazole Derivative for Amine Sensing and Anti‐Counterfeiting Applications
- Author
-
Wai Yeung Wong, Qiguang Zang, Heyi Yang, Gaofeng Bian, Jingwei Sun, Cheng Zhang, Zhongfu An, Huili Ma, and Yujian Zhang
- Subjects
Materials science ,Photoluminescence ,Molecular Structure ,010405 organic chemistry ,General Chemistry ,General Medicine ,Triazoles ,Chromophore ,010402 general chemistry ,Excimer ,Photochemistry ,01 natural sciences ,Fluorescence ,Catalysis ,0104 chemical sciences ,Wavelength ,Excited state ,Molecule ,Amines ,Excitation - Abstract
Excitation wavelength dependent (Ex-De) emission materials have potential applications in anti-counterfeiting labels and bioimaging. Nevertheless, few purely organic chromophores are used in these areas. In this study, multiple excited states were incorporated into a molecule that was excited state intramolecular proton transfer (ESIPT) active, with the goal of manipulating the relaxation pathways of the excited states. The triazole derivative exhibits Ex-De photoluminescence (PL), and the maximum PL wavelength is located at 526 nm and 593 nm under a series of excitation wavelengths. Spectral identification indicates that the excimer and ESIPT processes are responsible for the green (526 nm) and orange (593 nm) fluorescence, respectively. Importantly, the quick response code and test strip prepared with this triazole derivative can be used for anti-counterfeiting and food spoilage detection applications, respectively. This research opens the door for developing novel Ex-De materials for anti-counterfeiting purposes.
- Published
- 2019
166. Program controlling the emission color of blend polymer phosphors containing Eu(III), Tb(III), Be(II) ions for WLEDs
- Author
-
Qian Yan, Wai Yeung Wong, Yanqin Miao, Zhi Wang, Wei Xu, Aiqin Zhang, Ruibo Chen, Husheng Jia, and Bingshe Xu
- Subjects
Materials science ,Analytical chemistry ,Phosphor ,02 engineering and technology ,Color temperature ,010402 general chemistry ,01 natural sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Chromaticity ,Methyl methacrylate ,Spectroscopy ,chemistry.chemical_classification ,Organic Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Color rendering index ,chemistry ,RGB color model ,0210 nano-technology ,Luminescence - Abstract
Through of the technique route of pre-coordination and post-polymerization and final-blend by program controlling from vinyl-functionalized RGB complex monomers [Eu(TTA)3(UA)](TTA = 2-thenoyltrifluoroacetone, UAH= Undecenoic acid), [Tb(2-ABA)3(UA)](2-ABAH = 2-Aminobenzoic acid), [Be (BTZ) (MAA)](BTZ=Benzothiazole, MAA = Methylacrylic acid) with Methyl methacrylate(MMA) to synthesize the monochrome polymers poly(MMA-co-Eu(TTA)3(UA)) (abbr. PMEu), poly(MMA-co-Tb(2-ABA)3(UA)) (abbr. PMTb), poly(MMA-co- Be (BTZ) (MAA)) (abbr. PMBe), and finally obtain the white-light blend-polymer phosphors by program controlling. The monochrome polymers PMEu, PMTb, PMBe have 1.69, 11.53, 10.57 times of the luminescent intensity as RGB complex monomers. The serial blend polymer phosphors have the emission located in the white light region with the CIE coordinates close to the calculated ones running by the program. When the RGB ratio = 1:1.38:0.46, the experiment coordinates are situated at (0.32, 0.33), being close to the theoretical coordinates of (0.33, 0.33), proving that the program controlling can guide the tuning of the chromaticity of the emission color. The LED device was fabricated by the blend polymer phosphor with the RGB ratio of 1:1.38:0.46 matched with the chip of 365 nm wavelength, the color temperature is 6444 K, the color rendering index 84.2, and the luminance 12740 cd/m2 at 3.2 V. This research develops an approach of pre-coordination, post-polymerization and final-blend by program controlling that not only improves the luminescent intensity, but also suppresses the energy transfer, and more importantly achieves the precise adjustment to the white light.
- Published
- 2019
167. An inorganic magnetic fluorescent nanoprobe with favorable biocompatibility for dual-modality bioimaging and drug delivery
- Author
-
Yixia Zhang, Ruiping Zhang, Qingchen Dong, Baofeng Yu, Feifei Tai, Hongen Guo, Wai Yeung Wong, and Wenting Liang
- Subjects
Fluorescence-lifetime imaging microscopy ,Biocompatibility ,010405 organic chemistry ,Chemistry ,Contrast Media ,Nanoprobe ,010402 general chemistry ,Magnetic Resonance Imaging ,01 natural sciences ,Biochemistry ,Fluorescence ,0104 chemical sciences ,Nanoclusters ,Inorganic Chemistry ,Drug Delivery Systems ,Targeted drug delivery ,Doxorubicin ,Stomach Neoplasms ,Cell Line, Tumor ,Drug delivery ,Biophysics ,Humans ,MTT assay ,Gold ,Magnetite Nanoparticles - Abstract
In this work, we present the development of a high water soluble biological nanoprobe through the covalent bonding of β-CD onto the surface of iron oxide‑gold nanoclusters (Fe3O4@Au@β-CD). Fe3O4@Au@SiO2 NPs were also prepared for comparison. The maximum emission peak of magnetic fluorescent NPs red-shifted by 30 nm and the lifetime was also elongated to 5.21 μs after surface modified with β-CD. The relaxivities and in vitro magnetic resonance imaging ability of the resultant magnetic fluorescent NPs were also studied, indicating that Fe3O4@Au@β-CD NPs have the lowest r2/r1 ratio and could be a potential T2 contrast agent for MR imaging. The MTT assay proved that, Fe3O4@Au@β-CD NPs are of excellent water solubility and biocompatibility. In vitro confocal fluorescence imaging was also performed, manifesting that Fe3O4@Au@β-CD NPs can be selectively uptaken by gastric cancer cells (MGC-803) and exhibit red fluorescence in the cells. The preliminary drug loading and releasing measurements demonstrate that it can also act as targeted drug delivery nanosystem. All these experimental results indicate that, Fe3O4@Au@β-CD NPs hold great application perspective in the diagnosis and therapy of gastric cancer cells as biological nanoprobes.
- Published
- 2019
168. Achieving efficient inverted perovskite solar cells with excellent electron transport and stability by employing a ladder-conjugated perylene diimide dimer
- Author
-
Junle Qu, Yuren Xiang, Shuai Ye, Jun Song, Wai Yeung Wong, Xiao Peng, Helin Wang, and Fu Yang
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Dimer ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,Conjugated system ,021001 nanoscience & nanotechnology ,Electron transport chain ,chemistry.chemical_compound ,chemistry ,Diimide ,Thiophene ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Perylene ,Perovskite (structure) - Abstract
The lack of organic electron transport materials (ETM) with excellent electron transport and device stability is an important problem for the development and commercialization of perovskite solar cells (PSCs). Herein, a ladder-conjugated perylene diimide dimer containing an indacenodithiophene unit, namely IDTT2FPDI, was synthesized in two steps with high yields. In addition, IDTT2FPDI exhibits suitable energy levels, high electron mobility, and an excellent hydrophobicity because of its multiple fused thiophene rings and large ladder-conjugated framework. Compared with inverted PSCs which typically use PCBM as a single electron transport layer (ETL), the device utilizing IDTT2FPDI/PCBM as a double ETL showed a better power conversion efficiency (PCE) of 19.4%. Moreover, the double ETL-based devices exhibited superior stability compared with the single ETL-based devices due to the hydrophobicity of the IDTT2FPDI layer. These results highlight the potential of employing ladder-conjugated PDI dimers as ETMs to obtain high-efficiency and stable PSCs, which shows promise for the development of PSCs.
- Published
- 2019
169. A novel Na3La(PO4)2/LaPO4:Eu blue-red dual-emitting phosphor with high thermal stability for plant growth lighting
- Author
-
Wai Yeung Wong, Zhi Zhou, Yuan Zhong, Mao Xia, and Wu Xianbo
- Subjects
Materials science ,Photoluminescence ,Analytical chemistry ,Phosphor ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Spectral line ,0104 chemical sciences ,law.invention ,LED lamp ,law ,Materials Chemistry ,Thermal stability ,Emission spectrum ,0210 nano-technology ,Luminescence ,Powder diffraction - Abstract
A novel Na3La2(PO4)3:xEu (Na3La(PO4)2/LaPO4:xEu) blue-red dual-emission diphasic phosphor with high thermal stability is successfully synthesized by a high temperature solid state reaction. X-ray powder diffraction (XRD) analysis verified that the host of this dual emitting phosphor is a composite material composed of two crystals: Na3La(PO4)2 and LaPO4, which would realize the energy transfer between the two phases and then greatly enhance the luminescence properties. When compared with the single-phase phosphor Na3La(PO4)2:xEu, the photoluminescence (PL) spectra of the as-synthesized diphasic phosphor showed significantly enhanced blue emission peaking at 422 nm of Eu2+ (5d-4f, a broadband at around 422 nm) and red emission peaking at 594 nm of Eu3+ (5D0–7F1,2, 594 and 621 nm) under UV excitation. Moreover, the phosphor exhibited a high thermal stability at 150 °C with up to 98.5% luminescence retention after Li+ co-doping, which should be attributed to the introduction of several defects. The emission spectra matched well with the photosynthetic action spectra (PAS) in plants, indicating that the Na3La2(PO4)3:xEu phosphor has a promising application in plant growth LED lighting.
- Published
- 2019
170. Pure E/Z isomers of N-methylpyrrole-benzohydrazide-based BF2 complexes: remarkable aggregation-, crystallization-induced emission switching properties and application in sensing intracellular pH microenvironment
- Author
-
Erhong Hao, Wai Yeung Wong, Qinghua Wu, Yizhe Yu, Hua Wang, Lijuan Jiao, and Changjiang Yu
- Subjects
Materials science ,Photoisomerization ,Substituent ,Aromaticity ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Single bond ,Molecule ,Methylene ,0210 nano-technology ,Conformational isomerism ,Isomerization - Abstract
Organic fluorescent molecules with E/Z isomers usually have different photophysical properties owing to their disparate configurations, which lead to differences in molecular polarity and the chemical environment of atoms. However, due to the difficulty in the synthesis of their pure E and Z conformers, very limited research efforts have been devoted to studying the different photophysical properties of these isomers. In this work, two pairs of pure E/Z isomers of novel fluoroboron acylhydrozone dyes based on 2,2-difluoro-3-[(N-methylpyrrol-2-yl)methylene]-5-phenyl-1,3,4,2-oxadiazaborole (MPOAB) with two different electronic substituent groups (OMe or NEt2) were developed for the first time. These isomers were each characterized by NMR, X-ray structure analysis, HRMS, and absorption and PL spectroscopy. All isomers showed weak fluorescence properties in organic solvents and strong fluorescence in the solid state as well as excellent aggregation-induced emission (AIE) properties. More interestingly, the photophysical properties of the E/Z isomers, especially their aggregation and crystallization-induced emission, are significantly different. These results indicate that the AIE properties of these compounds are mainly attributed to the restriction of single bond rotations between the two aromatic rings and the five-membered fluoroboric ring, while participation of E/Z isomerization is finite. Besides, their photoisomerization, grinding, viscosity, and acid–base fluorescence response properties were also studied. In addition, an isomer of them, as an example, was successfully applied for analyzing the intracellular pH microenvironment of living cancer cells.
- Published
- 2019
171. Design of wide-bandgap polymers with deeper ionization potential enables efficient ternary non-fullerene polymer solar cells with 13% efficiency
- Author
-
Gang Li, Hongzheng Chen, Hang Yin, Tsz-Ki Lau, Shu Kong So, Lingling Zhan, Wai Yeung Wong, Jianhui Hou, Ying Zhang, Xinhui Lu, Shaoqing Zhang, Delong Liu, and Patrick W. K. Fong
- Subjects
chemistry.chemical_classification ,Organic electronics ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Band gap ,02 engineering and technology ,General Chemistry ,Polymer ,Conjugated system ,Electron acceptor ,021001 nanoscience & nanotechnology ,Polymer solar cell ,chemistry ,Optoelectronics ,General Materials Science ,Quantum efficiency ,0210 nano-technology ,business ,Ternary operation - Abstract
Two regioisomeric wide-bandgap (WBG) polymers, PDBT(E)BTz-p and PDBT(E)BTz-d, with different nitrogen topologies along the conjugated backbone were developed and applied in non-fullerene polymer solar cells. Both polymers exhibit deeper ionization potential (IP) enabled by the synergistic electron-withdrawing effect of chlorine atoms and ester substituents. The effects of different nitrogen topologies on polymeric backbone linearity and optoelectronic and photovoltaic properties are systematically investigated. When blended with the electron acceptor IT-4F, the PDBT(E)BTz-p-based device delivers a PCE of 6.96% with a high VOC of 0.98 V and a low energy loss of 0.55 eV, while the PDBT(E)BTz-d-based device exhibits a higher PCE of 7.81% with an improved FF. Furthermore, PDBT(E)BTz-d is found to be effective as the third component in a binary PBDB-T-SF:IT-4F system to enhance device efficiencies from 12.1% for the binary device to 13.4% for the ternary device with 5 wt% PDBT(E)BTz-d relative to PBDB-T-SF. It is observed that an internal Forster resonance energy transfer (FRET) between PDBT(E)BTz-d and PBDB-T-SF gives rise to the improvement of external quantum efficiency and JSC. These results demonstrate that the WBG polymer featuring deeper IP can not only enhance the VOC but can also act as a sensitizer to transfer energy through the FRET mechanism toward highly efficient ternary PSCs. In addition, this contribution provides a new idea for the design and synthesis of conjugated polymers for organic electronics.
- Published
- 2019
172. Rational design of high efficiency green to deep red/near-infrared emitting materials based on isomeric donor–acceptor chromophores
- Author
-
Jun Song, Junle Qu, Youming Zhang, Jiatao Wu, Junjie He, Zhao Chen, Xin Wang, Wai Yeung Wong, and Shuming Chen
- Subjects
Photoluminescence ,Materials science ,Doping ,Near-infrared spectroscopy ,02 engineering and technology ,General Chemistry ,Electroluminescence ,Chromophore ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Wavelength ,Materials Chemistry ,OLED ,0210 nano-technology - Abstract
A family of compounds TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph with an isomeric donor–acceptor conjugation framework were designed and synthesized, and their structure–property relationships, theoretical calculations, and photophysical and electrochemical characteristics were investigated. These isomeric chromophores showed significantly different photophysical properties. Emission wavelengths spanning from the green to near-infrared region were observed in different solvents with high photoluminescence quantum yields, exceeding 90% in low polarity solvents and 44–88% in blend films. Organic light-emitting devices (OLEDs) displayed a strong electroluminescence with emission peaks at 592, 660, 630, and 580 nm; maximum current efficiencies of 7.92, 2.93, 3.56, and 15.37 cd A−1; maximum power efficiencies of 4.21, 1.56, 1.81, and 8.24 lm W−1; and maximum external quantum efficiencies of 3.15%, 2.75%, 2.66%, and 5.33% for TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph doped OLEDs, respectively.
- Published
- 2019
173. Imidazole-containing cyanostilbene-based molecules with aggregation-induced emission characteristics: photophysical and electroluminescent properties
- Author
-
Yujie Dong, Wenjing Tian, Bin Xu, Cheuk Lam Ho, Nianyong Zhu, Yang Liu, Jingyu Qian, and Wai Yeung Wong
- Subjects
02 engineering and technology ,General Chemistry ,Conjugated system ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Intramolecular force ,Materials Chemistry ,Imidazole ,Moiety ,Molecule ,Quantum efficiency ,0210 nano-technology ,Luminescence - Abstract
Organic luminogens with aggregation-induced emission (AIE) characteristics have recently attracted great research interest due to their excellent luminescence behavior in the aggregate state. Cyanostilbene is a well-known AIE-active moiety due to its unique luminescence mechanism and widespread use in the design of optical materials. In this work, we report two symmetrical imidazole-containing cyanostilbene derivatives with AIE activity, abbreviated as TPIA and PPIA, whose chemical structures only differ by a C–C bond. Both molecules are thermally stable and fabricated as electroluminescent (EL) devices. On one hand, the study of their photophysical properties confirms that the restricted intramolecular rotation (RIR) effect is still the dominant factor for the AIE effect in these two cyanostilbene-based molecules. On the other hand, the EL results reveal that a more conjugated molecular structure is beneficial for the EL properties. Moreover, the optimization of the device configuration with an electron-blocking layer significantly improves the EL performance. The orange-emissive PPIA-based device shows a high external quantum efficiency of 1.02% with a small efficiency roll-off.
- Published
- 2019
174. A single component white electroluminescent device fabricated from a metallo-organic terbium complex
- Author
-
Wai Yeung Wong, Rashid Ilmi, Liang Zhou, Paul R. Raithby, Muhammad S. Khan, and Weidong Sun
- Subjects
Brightness ,Materials science ,Doping ,Analytical chemistry ,Oxide ,chemistry.chemical_element ,Ether ,Terbium ,02 engineering and technology ,General Chemistry ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,OLED ,Quantum efficiency ,0210 nano-technology - Abstract
Two new mixed ligand complexes [Eu(tfac)3(DPEPO)] (Eu-1) and [Tb(tfac)3(DPEPO)] (Tb-2) incorporating trifluoroacetylacetone (Htfac) and bis(2-(diphenylphosphino)phenyl)ether oxide (DPEPO) were synthesized in gram-scale quantities and used as emitters to fabricate single- and double-EML (light-emitting layer) electroluminescence (EL) devices. The single-EML device with the structure: ITO/HAT-CN (6 nm)/HAT-CN (0.2 wt%):TAPC (50 nm)/Eu-1 (1–6 wt%): 26DCzPPy (10 nm)/Tm3PyP26PyB (50 nm)/LiF (1 nm)/Al (100 nm) showed light red (CIE, x: 0.574; y: 0.275) emission for the Eu-1 based EL devices due to the presence of a host emission with a brightness of 1274 cd m−2, current efficiency (ηc), power efficiency (ηp) and external quantum efficiency (EQE) of 0.58 cd A−1, 0.68 lm W−1, and 0.70%, respectively. The single-EML device for the Tb-2 complex with the same device structure displayed white-light emission. The optimized single-EML device of Tb-2 with 14.0 wt% doping concentration showed an impressive EL performance with brightness of 1637 cd m−2, ηc ≈ 3.05 cd A−1, ηp ≈ 2.80 lm W−1, EQE ≈ 1.4%, Vturn-on ≈ 3.1 V, respectively. This is the first report of single component white organic light emitting diode (W-OLED) fabricated from an organo-Tb(III) complex. The W-OLEDs show low turn-on voltages (Vturn-on) ≈ 3.1 V and are thus advantageous in lowering the power consumption of the OLED display.
- Published
- 2019
175. Electrochromic triphenylamine-based cobalt(<scp>ii</scp>) complex nanosheets
- Author
-
Ryota Sakamoto, Hiroshi Nishihara, Cheuk Lam Ho, Wai Yeung Wong, and Yurong Liu
- Subjects
Materials science ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Triphenylamine ,01 natural sciences ,0104 chemical sciences ,Ion ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Electrochromism ,Mechanical strength ,Materials Chemistry ,Terpyridine ,0210 nano-technology ,Cobalt ,Large size - Abstract
Two bottom-up Co(II) complex nanosheets Co-S1 and Co-S2 were prepared by coordination of trifunctional terpyridine-based triphenylamine derivatives (L1 and L2) and a cobalt(II) ion, in order to demonstrate the structural flexibility and functional tunability of these nanosheets over the top-down type. A liquid–liquid interface-assisted synthesis was employed, which is a facile method to generate multi-layer nanosheets. The nanosheets formed were characterized, revealing the proposed sheet morphology and uniform composition. They have large size domains and good mechanical strength. Besides, both Co-S1 and Co-S2 show reversible electrochromism. The color of Co-S1 was switched from red to green while that of Co-S2 was changed from light red to orange when a positive voltage was applied. An electrochromic device was also fabricated with Co-S1, indicating the promising application of these kinds of structurally tunable, easy-processable and stable nanosheets as low-cost and solid-state electrochromic materials.
- Published
- 2019
176. A new strategy to synthesize three-coordinate mononuclear copper(<scp>i</scp>) halide complexes containing a bulky terphenyl bidentate phosphine ligand and their luminescent properties
- Author
-
Xin Xin Zhong, Li Liu, Fa Bao Li, Wai Yeung Wong, Lei Wang, Rui Zhang, Hengjiang Cong, Li Ping Liu, Yi Zhao, Njud S. Alharbi, and Guang Hua Li
- Subjects
Denticity ,Diphenylphosphine ,Chemistry ,Ligand ,chemistry.chemical_element ,Halide ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Microsecond ,Crystallography ,Terphenyl ,Materials Chemistry ,0210 nano-technology ,Phosphine - Abstract
Highly emissive three-coordinate copper(I) complexes have received much attention. Here, a new synthetic strategy for the preparation of a bulky terphenyl bidentate phosphine ligand mpdp is presented. A series of mononuclear three-coordinate Cu(I) halide complexes [CuX(mpdp)] (mpdp = 4,4′,4′′,5,5′,5′′–hexamethyl-(1,1′:2′,1′′-terphenyl)-2,2′′-bis(diphenylphosphine), X = I (1), Br (2) and Cl (3)), were synthesized. This method provides a three-coordinate linkage between the bulky bidentate phosphine ligand and CuX. These complexes exhibit green to yellow green emission in the solid state at room temperature and have peak emission wavelengths at 493–533 nm with microsecond lifetimes (τ = 7.2–415.9 μs). Small S1–T1 energy gaps in the solid state indicate that the emission occurs from a thermally activated excited singlet state at ambient temperature. The emission of complexes 1–3 mainly originates from MLCT and XLCT transitions. The solution-processed devices of complex 1 exhibit yellow emission with a CIE (x, y) of (0.44, 0.47).
- Published
- 2019
177. Towards high performance solution-processed orange organic light-emitting devices: precisely-adjusting properties of Ir(<scp>iii</scp>) complexes by reasonably engineering the asymmetric configuration with second functionalized cyclometalating ligands
- Author
-
Guijiang Zhou, Zhaoxin Wu, Xiaolong Yang, Yan Li, Yuanhui Sun, Jingshuang Dang, Boao Liu, and Wai Yeung Wong
- Subjects
Photoluminescence ,Materials science ,business.industry ,Ligand ,Quantum yield ,02 engineering and technology ,General Chemistry ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Materials Chemistry ,OLED ,Optoelectronics ,Quantum efficiency ,0210 nano-technology ,business ,Phosphorescence ,Electrical efficiency - Abstract
The property-tuning of phosphorescent organometallic Ir(III) complexes is a crucial issue in developing high performance electroluminescent materials. Unlike the conventional strategy that usually regulates the properties of symmetric tri-/bis-cyclometalated Ir(III) complexes by modifying the structure of the cyclometalating ligands, we herein report the method of tuning properties by reasonably engineering the asymmetric configuration of Ir(III) complexes. Taking the newly synthesized conventional symmetric bis-cyclometalated Ir(III) complex SIrS as a reference, the emission properties such as the emission color, radiative lifetime (τr), and the photoluminescence quantum yield (PLQY) as well as charge transport properties can be tuned step by step by reasonably choosing the second functionalized cyclometalating ligand. The photophysical measurements and theoretical calculations reveal that the adjustment of emission properties results from the switches of the low energy charge transfer characteristics. Accordingly, the optimized asymmetric complex SIrB displays the highly desirable orange emission with a high PLQY of 0.96, a short τr of 0.38 μs, and significantly enhanced electron injection/transport abilities. More importantly, the solution-processed orange organic light-emitting device (OLED) based on SIrB exhibits excellent electroluminescence (EL) performance with a maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 23.2%, 66.5 cd A−1, and 56.0 lm W−1, respectively, which are among the best reported for state-of-the-art solution-processed orange OLEDs. This study demonstrates the importance of the asymmetric configuration engineering strategy for developing phosphorescent Ir(III) complexes with outstanding EL performance.
- Published
- 2019
178. Synthesis, photoluminescence and electroluminescence of triphenylphosphine functionalized cyclometalated iridium(III) complexes
- Author
-
Hongbo Fan, Wai Yeung Wong, Cheuk Lam Ho, Dongge Ma, Shoushan Wang, Liqi Wang, Peng Liu, and Guiping Tan
- Subjects
Photoluminescence ,Materials science ,Process Chemistry and Technology ,General Chemical Engineering ,chemistry.chemical_element ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Pyridine ,OLED ,Physical chemistry ,Quantum efficiency ,Iridium ,Triphenylphosphine ,0210 nano-technology ,Phosphorescence - Abstract
Three greenish-blue iridium (III) phosphorescent complexes with the molecular structure of [Ir(pppy)2(PPh3)L] (Hpppy = 2-(4-phenoxyphenyl)pyridine; L = Cl−, NCS−, NCO−) were synthesized and characterized. Their photoluminescence spectra are significantly blue-shifted after introducing the strong-field ancillary ligand triphenylphosphine. These compounds exhibit emission peaks in the range of 474–479 nm in solutions at 298 K with quantum yields up to 0.33. The organic light-emitting diodes (OLEDs) were fabricated by thermal evaporation with complex 3. The best OLED D3 was obtained with turn-on voltage of 4.3 V, maximum luminance of 11931 cd m−2 under 15.7 V, highest luminance efficiency (ηL) as 16.6 cd A−1, power efficiency (ηP) as 12.2 lm W−1 and external quantum efficiency (EQE) as 5.6%.
- Published
- 2019
179. A novel family of AIE-active meso-2-ketopyrrolyl BODIPYs: bright solid-state red fluorescence, morphological properties and application as viscosimeters in live cells
- Author
-
Wai Yeung Wong, Zhenlong Huang, Wei Gu, Yi Xiao, Changjiang Yu, Qinghua Wu, Erhong Hao, and Lijuan Jiao
- Subjects
Quantum yield ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,Condensation reaction ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,chemistry.chemical_compound ,Viscosity ,chemistry ,Oxalyl chloride ,Intramolecular force ,Materials Chemistry ,General Materials Science ,BODIPY ,0210 nano-technology - Abstract
Fluorescent probes towards viscosity determination can be used to report on variations in local molecular viscosity and have become valuable tools for the study of intracellular microenvironments. Herein, we develop a family of remarkable meso-2-ketopyrrolyl-derived BODIPY rotors and report a new strategy for building them via simple condensation reactions between oxalyl chloride and substituted pyrroles. They are well characterized by NMR, HRMS, crystal structure, spectroscopic and morphological studies. These uncommon meso-2-ketopyrrolyl-derived BODIPYs are weakly fluorescent in their organic solutions but exhibit bright solid-state red fluorescence from 620 to 661 nm with a maximum fluorescence quantum yield of 25%. All of them also exhibit notable aggregation-induced emission (AIE)-active features. Interestingly, the formed nanoaggregates were observed to exhibit morphological distinctions owing to different substituents. The fluorescence enhancement towards the increased viscosity of the environment might be mainly attributed to the restriction of their intramolecular rotations of the meso-ketopyrrolyl groups. More interestingly, the increase in the fluorescence lifetime of these representative rotors appears to perfectly correlate with the increase in the viscosity of the media, and they have been used as viscosimeters for real-time quantitative determination of the variation of the intracellular viscosity in live cells. The easy synthetic strategy and real-time quantitative determination of the variation pave a new way for creating fluorescent molecular rotor materials.
- Published
- 2019
180. Efficient white polymer light-emitting diodes (WPLEDs) based on double emitting layers of a PVK:Eu(<scp>iii</scp>)-complex and Alq3
- Author
-
Guorui Fu, Lin Liu, Xingqiang Lü, Hongshan He, Yani He, Wai Yeung Wong, and Wentao Li
- Subjects
chemistry.chemical_classification ,Materials science ,Dibenzoylmethane ,business.industry ,Doping ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polymer light emitting diodes ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Optoelectronics ,0210 nano-technology ,business ,Layer (electronics) ,Diode - Abstract
Colour-tunable polymer light-emitting diodes (PLEDs) were realized by tuning the concentration of an Eu3+-complex in the emitting-layer (EML) and the thickness of the hole-blocking BCP layer (BCP = 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) in a double-emitting-layer (dEML) configuration. The dEML used PVK:complex 2 (PVK = poly(N-vinylcarbazole); H2Salen = N,N′-bis(salicylidene)cyclohexane-1,2-diamine and HDBM = dibenzoylmethane for [Zn(Salen)(μ-OAc)Eu(DBM)2] (2)) as EML1 and Alq3 as EML2. The efficiencies (0.32–0.39 cd A−1, 0.54–0.56% and 0.99–1.10 lm W−1) were obtained from organo-Eu3+ incorporated WPLEDs with a complex-2-doping content of 20 or 30 wt% and 20 nm BCP thickness. The WPLEDs exhibited low turn-on voltage (6.0–7.5 V) and low efficiency-roll-off, which are advantageous to organo-Eu3+ doped WOLEDs.
- Published
- 2019
181. Reversible two-channel mechanochromic luminescence for a pyridinium-based white-light emitter with room-temperature fluorescence–phosphorescence dual emission
- Author
-
Wai Yeung Wong, Chensheng Lin, Yangbin Xie, Dayu Wu, Guo-Liang Chai, Xiao Ma, Jipeng Li, and Wei Huang
- Subjects
Mechanochromic luminescence ,Materials science ,General Physics and Astronomy ,Quantum yield ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Molecule ,Pyridinium ,Physical and Theoretical Chemistry ,0210 nano-technology ,Luminescence ,Phosphorescence ,Common emitter - Abstract
Organic mechanochromic luminescent (ML) materials have attracted extensive interest due to their potential uses in displays, sensing, bioimaging and data storage. ML materials that distinctively respond to different mechanical stimuli are especially fascinating. A simple pyridinium-based white-light emitter (P1-PF6) exhibiting this sort of ML with room-temperature fluorescence-phosphorescence dual emission (rFPDE) was found to possess a 3.66% quantum yield. Interestingly, mechanical grinding induced phosphorescence disappearance owing to a collapse of the crystalline ordering. Grinding followed by adding a drop of ethanol resulted in an extraordinary tricolor emission switching between white, blue and pinkish orange. More interestingly, mechanical pressing induced phosphorescence enhancement, resulting in the emission color changing from white to pinkish orange. This novel phenomenon may be due to the fact that pressure facilitates a closer arrangement between adjacent molecules, thereby enhancing the intermolecular interactions. In sum, a very scarce example is herein reported. Moreover, because the pure organic pyridinium with rFPDE achieves reversible two-channel ML over a wide wavelength range, this material has potential applications in multi-dimensional sensors.
- Published
- 2019
182. Efficient polymer light-emitting diodes (PLEDs) based on chiral [Pt(C^N)(N^O)] complexes with near-infrared (NIR) luminescence and circularly polarized (CP) light
- Author
-
Wentao Li, Guorui Fu, Yani He, Baowen Wang, Hongshan He, Wai Yeung Wong, and Xingqiang Lü
- Subjects
chemistry.chemical_classification ,Materials science ,business.industry ,Near-infrared spectroscopy ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polymer light emitting diodes ,0104 chemical sciences ,3. Good health ,chemistry ,Materials Chemistry ,Optoelectronics ,0210 nano-technology ,Luminescence ,business ,Diode - Abstract
Chiral NIR-light emitters [Pt(iqbt)(S-Ln)] (1–4) were used as dopants to produce CP-NIR-PLEDs displaying λem of 732 nm, ηMaxEQE of 0.87–0.93%, and gEL of up to 10−3.
- Published
- 2019
183. AIE-active difluoroboronated acylhydrozone dyes (BOAHY) emitting across the entire visible region and their photo-switching properties
- Author
-
Qinghua Wu, Jiahua Li, Xingbao Fang, Wai Yeung Wong, Erhong Hao, Changjiang Yu, Lijuan Jiao, Linli Xu, and Long Wang
- Subjects
Materials science ,Photoisomerization ,Quantum yield ,02 engineering and technology ,General Chemistry ,Chromophore ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Green fluorescent protein ,Planar ,Intramolecular force ,Materials Chemistry ,Single bond ,0210 nano-technology - Abstract
A new family of difluoroboronate anchored acylhydrozones, named BOAHY, have been developed as green fluorescent protein (GFP) chromophore analogues via a simple one-pot two-step reaction in moderate to good yields. They were well characterized by NMR, HRMS, X-ray crystallography and various spectroscopic techniques. These BOAHYs are weakly fluorescent in their solutions but emit brightly in the powder and film states across the entire visible region, with a maximum fluorescence quantum yield of 62%. They also exhibit notable aggregation-induced emission (AIE)-active features. Photoisomerization transformation under strong UV light irradiation at 365 nm as well as the viscosity-dependent fluorescence changes, indicate that the restriction of the intramolecular free rotation of the single bonds at the periphery is the main cause for the novel AIE process of these BOAHYs. In addition, the Z/E photoisomerization was studied for their potential application as photoswitching materials. UV light irradiation at 365 nm caused obvious fluorescence changes, and the photoisomerization was found to be reversible in a dark environment, which paves a new way for creating fluorescent photoswitches based on these planar conformations.
- Published
- 2019
184. High‐Performance Inverted Tandem OLEDs with the Charge Generation Layer based on MoO x and Ag Doped Planar Heterojunction (Advanced Optical Materials 16/2022)
- Author
-
Yachen Xu, Yixiao Niu, Chunliu Gong, Wei Shi, Xuyong Yang, Bin Wei, and Wai‐Yeung Wong
- Subjects
Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
185. KBF 4 Additive for Alleviating Microstrain, Improving Crystallinity, and Passivating Defects in Inverted Perovskite Solar Cells
- Author
-
Haiyang Cheng, Chunki Liu, Jing Zhuang, Jiupeng Cao, Tianyue Wang, Wai‐Yeung Wong, and Feng Yan
- Subjects
Biomaterials ,Electrochemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
186. Synthesis, characterization and thermoelectric properties of new non-conjugated nitroxide radical-containing metallopolymers
- Author
-
Mei-Tung Lau, Zikang Li, Zelin Sun, and Wai-Yeung Wong
- Subjects
Polymers and Plastics ,Organic Chemistry ,Materials Chemistry - Published
- 2022
187. A cyanostilbene-based molecule with aggregation-induced emission properties: amplified spontaneous emission, protonation effect and electroluminescence
- Author
-
Bin Xu, Wai Yeung Wong, Nianyong Zhu, Yujie Dong, Cheuk Lam Ho, Xiaoyu Zhang, Wenjing Tian, Suqian Ma, and Jingyu Qian
- Subjects
Amplified spontaneous emission ,Materials science ,Protonation ,02 engineering and technology ,General Chemistry ,Electroluminescence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,Deprotonation ,Molecule ,0210 nano-technology ,Lasing threshold ,Single crystal - Abstract
A terpyridine-substituted cyanostilbene derivative ( Z )-2-(4 ¢ -([2,2 ¢ :6 ¢ ,2 ² -terpyridin]-4 ¢ -yl)-[1,1 ¢ -biphenyl]-4-yl)-3-phenylacrylonitrile ( CNSTPy ) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission (ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ~1.5 mJ cm−2. The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.
- Published
- 2018
188. Effect of the Linking Group on the Thermoelectric Properties of Poly(Schiff Base)s and Their Metallopolymers
- Author
-
Zitong Wang, Jiahua Li, Zelin Sun, Linli Xu, and Wai Yeung Wong
- Subjects
Conductive polymer ,chemistry.chemical_classification ,Schiff base ,010405 organic chemistry ,Band gap ,Organic Chemistry ,Composite number ,Doping ,General Chemistry ,Carbon nanotube ,Polymer ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Thermoelectric effect - Abstract
As polymer-based thermoelectric (TE) materials possess attractive features such as light weight, flexibility, low toxicity and ease of processibility, an increasing number of conducting polymers and their composites with high TE performances have been developed in recent years. Up to date, however, the research focusing on the structure-performance relationship remains rare. In this paper, two series of poly(Schiff base)s with either C=C or C≡C linker and their metallopolymers were synthesized and doped with single-walled carbon nanotubes to evaluate how the linking groups affected the TE properties of the resulting composites. Apart from the effect exerted by the morphology, experimental results suggested that the linkers played a key role in determining the band gaps, preferred molecular conformation and extent of conjugation of the polymers, which became key factors that influenced the TE properties of the resulting materials. Additionally, upon coordination with transition metal ions, the TE properties could be tuned readily.
- Published
- 2021
189. Largely Color-Tuning Prompt and Delayed Fluorescence: Dinuclear Cu(I) Halide Complexes with
- Author
-
Ke, Xu, Bu-Lin, Chen, Fei, Yang, Li, Liu, Xin-Xin, Zhong, Lei, Wang, Xun-Jin, Zhu, Fa-Bao, Li, Wai-Yeung, Wong, and Hai-Mei, Qin
- Abstract
Luminescent copper(I) halide complexes with bi- and tridentate rigid ligands have gained wide research interests. In this paper, six tetracoordinate dinuclear copper(I) halide complexes, Cu
- Published
- 2021
190. Optical and Optoelectronic Polymers
- Author
-
Wai-Yeung Wong, Yun Ma, Wai-Yeung Wong, and Yun Ma
- Abstract
The field of optoelectronic polymers has continuously expanded in the past two decades because of their innovative applications in a variety of technologies in optoelectronic, photonic and energy research. Groups across the world are still looking into the fundamentals, as well as their applications, which remain to be fully understood and envisioned. This is the first book on the topic for researchers who are entering the field, highlighting the remarkable basic science and technological potential of this class of materials. Chapters will focus on the fundamental concepts as well as up-and-coming research into the applications of these polymers. Chapters will look at topics such as pure organic phosphorescence and external stimuli-responsive luminescent materials that are not covered in other books.
- Published
- 2024
191. Metallated Graphynes as a New Class of Photofunctional 2D Organometallic Nanosheets
- Author
-
Mingzi Sun, Jianqi Zhang, Hongyang Zhang, Jiahua Li, Linli Xu, Wai Yeung Wong, Zhengping Wang, Jibin Sun, Bolong Huang, Zheng Xie, and Tianhong Tang
- Subjects
Fabrication ,Materials science ,010405 organic chemistry ,Graphene ,Nanotechnology ,Saturable absorption ,General Chemistry ,General Medicine ,010402 general chemistry ,01 natural sciences ,Catalysis ,Black phosphorus ,0104 chemical sciences ,law.invention ,Nanomaterials ,Graphyne ,law ,Optoelectronic materials - Abstract
Two-dimensional (2D) nanomaterials are attracting much attention due to their excellent electronic and optical properties. Here, we report the first experimental preparation of two free-standing mercurated graphyne nanosheets via the interface-assisted bottom-up method, which integrates both the advantages of metal center and graphyne. The continuous large-area nanosheets derived from the chemical growth show the layered molecular structural arrangement, controllable thickness and enhanced π-conjugation, which result in their stable and outstanding broadband nonlinear saturable absorption (SA) properties (at both 532 and 1064 nm). The passively Q-switched (PQS) performances of these two nanosheets as the saturable absorbers are comparable to or higher than those of the state-of-the-art 2D nanomaterials (such as graphene, black phosphorus, MoS2 , γ-graphyne, etc.). Our results illustrate that the two metallated graphynes could act not only as a new class of 2D carbon-rich materials, but also as inexpensive and easily available optoelectronic materials for device fabrication.
- Published
- 2021
192. Geodesic motion on $\mathsf{SL}(n)$ with the Hilbert-Schmidt metric
- Author
-
Samuel Sottile, Willie Wai Yeung Wong, and Audrey Rosevear
- Subjects
Mathematics - Differential Geometry ,Pure mathematics ,Geodesic ,010102 general mathematics ,Dimension (graph theory) ,Motion (geometry) ,Riemannian manifold ,01 natural sciences ,Exponential type ,Differential Geometry (math.DG) ,Bounded function ,0103 physical sciences ,Metric (mathematics) ,FOS: Mathematics ,Mathematics::Differential Geometry ,010307 mathematical physics ,Ideal (ring theory) ,0101 mathematics ,53C22 (Primary), 53A07, 53Z05, 53C25 (Secondary) ,Mathematics - Abstract
We study the geometry of geodesics on $\mathsf{SL}(n)$, equipped with the Hilbert-Schmidt metric which makes it a Riemannian manifold. These geodesics are known to be related to affine motions of incompressible ideal fluids. The $n = 2$ case is special and completely integrable, and the geodesic motion was completely described by Roberts, Shkoller, and Sideris; when $n = 3$, Sideris demonstrated some interesting features of the dynamics and analyzed several classes of explicit solutions. Our analysis shows that the geodesics in higher dimensions exhibit much more complex dynamics. We generalize the Virial-identity-based criterion of unboundedness of geodesic given by Sideris, and use it to give an alternative proof of the classification of geodesics in 2D obtained by Roberts--Shkoller--Sideris. We study several explicit families of solutions in general dimensions that generalize those found by Sideris in 3D. We additionally classify all "exponential type" geodesics, and use it to demonstrate the existence of purely rotational solutions whenever $n$ is even. Finally, we study "block diagonal" solutions using a new formulation of the geodesic equation in first order form, that isolates the conserved angular momenta. This reveals the existence of a rich family of bounded geodesic motions in even dimension $n \geq 4$. This in particular allows us to conclude that the generalization of the swirling and shear flows of Sideris to even dimensions $n \geq 4$ are in fact dynamically unstable., 3 figures; report from SURIEM 2020 Summer REU program. v2: journal accepted manuscript
- Published
- 2021
193. Recent Progress in the Selective Functionalization of P(O)–OH Bonds
- Author
-
Peng Cheng Qian, Biquan Xiong, Shipan Xu, Ke Wen Tang, Wai Yeung Wong, and Yu Liu
- Subjects
Esterification ,Chemistry ,Phosphorus ,chemistry.chemical_element ,Organic phosphorus ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Tautomer ,Catalysis ,0104 chemical sciences ,Organic molecules ,Small Molecule Libraries ,Transition metal ,Cyclization ,Metals ,Reagent ,Transition Elements ,Surface modification - Abstract
As we all know, organic phosphorus compounds have high application values in chemical industries. Compared with traditional compounds with P-X (X = Cl, Br, I) and P-H bonds, phosphorylation reagents containing P(O)-OH bonds are stable, environmentally friendly, and inexpensive. However, in recent years, there have been few studies on the selective functionalization of P(O)-OH bonds for the fabrication of P-C and P-Z bonds. In general, four-coordinated P(O)-OH compounds have reached coordination saturation due to the phosphorus atom center, but cannot evolve the phosphorus coordination center through intra-molecular tautomerization; however, the weak coordination effects between the P=O bond and transition metals can be utilized to activate P(O)-OH bonds. This review highlights the most important recent contributions toward the selective functionalization of P(O)-OH bonds via cyclization/cross coupling/esterification reactions using transition metals or small organic molecules as the catalyst.
- Published
- 2021
194. Metal-Free, Acid/Phosphine-Induced Regioselective Thiolation of
- Author
-
Biquan, Xiong, Shipan, Xu, Yu, Liu, Ke-Wen, Tang, and Wai-Yeung, Wong
- Abstract
A simple and efficient method for the regioselective thiolation of
- Published
- 2021
195. Branched Polymer Materials as Proton Exchange Membranes for Fuel Cell Applications
- Author
-
Boping Zhang, Sivasubramaniyan Neelakandan, Wai-Yeung Wong, Chunmei Gao, Lei Wang, Meishao Hu, Jiangpeng Ni, and Li Wang
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Proton ,Renewable Energy, Sustainability and the Environment ,Biomedical Engineering ,Synthetic membrane ,Proton exchange membrane fuel cell ,General Chemistry ,Polymer ,Electrolyte ,Electronic, Optical and Magnetic Materials ,Membrane ,chemistry ,Chemical engineering ,Materials Chemistry ,Fuel cells ,Electrical and Electronic Engineering ,Polyimide - Abstract
Recent progress on branched polymer membranes as electrolyte materials for proton exchange membrane fuel cell (PEMFC) applications has attracted interest due to the limitations of commercially available Nafion® membranes. Branched polymer membranes have shown improved chemical stability, proton conductivity, and good solubility. The branching degree and the structure of the branching agent have an essential correlation with the characteristics of the polymer membranes. This review presents the most recent and promising design strategies and characteristics of branched polymers as proton exchange membranes for both low- and high-temperature proton exchange membrane fuel cells. Recent advances in branched polymers are summarized, including branched sulfonated poly(aryl ether)s, branched sulfonated polyimides, branched polybenzimidazoles, etc. The remaining challenges and prospects in proton exchange membranes are also discussed.
- Published
- 2021
- Full Text
- View/download PDF
196. Development and advancement of iridium(III)-based complexes for photocatalytic hydrogen evolution
- Author
-
Daniel Nnaemaka Tritton, Fung-Kit Tang, Govardhana Babu Bodedla, Fu-Wa Lee, Chak-Shing Kwan, Ken Cham-Fai Leung, Xunjin Zhu, and Wai-Yeung Wong
- Subjects
Inorganic Chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry - Published
- 2022
197. Enhancing the Light Output‐Coupling of Inverted Top‐Emitting Organic Light‐Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles
- Author
-
Yunping Zhao, Yixiao Niu, Wei Shi, Zhen Zhang, Xuyong Yang, Bin Wei, Yudong Pang, and Wai‐Yeung Wong
- Subjects
Mechanics of Materials ,Mechanical Engineering - Published
- 2022
198. A comprehensive understanding on the roles of carbon dots in metallated graphyne based catalyst for photoinduced H2O2 production
- Author
-
Yajie Zhao, Linli Xu, Xiao Wang, Zhenzhen Wang, Yan Liu, Yang Wang, Qiaolian Wang, Zitong Wang, Hui Huang, Yang Liu, Wai-Yeung Wong, and Zhenhui Kang
- Subjects
Biomedical Engineering ,Pharmaceutical Science ,General Materials Science ,Bioengineering ,Biotechnology - Published
- 2022
199. Investigation of the Effects of Magnetic Additive Cobalt/Carboxyl functionalized Multi-walled Carbon Nanotubes for Enhancing the Machinability of Polycarbonate Composites under Magnetic Field
- Author
-
Ming, Gao, primary, Fai Cheung, Chi, additional, Bo, Wang, additional, and Wai Yeung, Wong, additional
- Published
- 2021
- Full Text
- View/download PDF
200. Soft salts based on platinum(II) complexes with high emission quantum efficiencies in the near infrared region for
- Author
-
Jun, Li, Yun, Ma, Suyi, Liu, Zhu, Mao, Zhenguo, Chi, Peng-Cheng, Qian, and Wai-Yeung, Wong
- Subjects
Anions ,Optical Imaging ,Static Electricity ,Transplantation, Heterologous ,Molecular Conformation ,Mice, Nude ,Mice ,Coordination Complexes ,Cations ,Neoplasms ,Animals ,Humans ,Quantum Theory ,HeLa Cells ,Platinum - Abstract
Two soft salts (S1 and S2) based on platinum(ii) complexes with a near-infrared emission have been designed and synthesized. It has been demonstrated that S2 has a high photostability and a low cytotoxicity, and it has been successfully applied to in vivo imaging for the first time.
- Published
- 2020
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.