Search

Photoinduced carrier dynamics of CsPbBr3 single crystalline perovskite films were studied using femtosecond time-resolved transient absorption (TA) microscopy with a sub-micron spatial resolution. TA spectra of the internal area and boundary of perovskite films were obtained, respectively, and photoinduced carrier dynamic processes including hot carrier cooling, defect state trapping and carrier recombination were elucidated by singular value decomposition (SVD) and global fitting analysis of the TA spectra. Compared with the internal region, excited state absorption induced by the defects at the boundary was observed, and the shorter lifetimes of photoinduced carriers were attributed to the large number of defect states accelerating the non-radiative recombination of carriers. This work may provide further understanding about the influence of boundary defects on the performance of single crystalline perovskite devices. [ABSTRACT FROM AUTHOR]

The separation of highly pure single-chirality single-walled carbon nanotubes (SWCNTs) is challenging and also in demand due to their intrinsic physical, optical, and electronic properties. The use of single-chirality and their performance characteristics makes them a selective candidate for multifunctional applications and opens a new front in nanotube development. It has previously been reported that SWCNTs can be separated in various ways by employing direct control and post-synthesis approaches. Herein, we review the separation of single-chiralities of SWCNTs on account of simplicity and time/cost effectiveness by using gel chromatography. The most recent progress in the controlled synthesis of SWCNTs is comprehensively reviewed in terms of selective-diameter, single-chirality, and specific geometric shape. The method to achieve the single-chirality of SWCNTs is also highlighted. Besides addressing COVID-19 characteristics, epidemiology, and pathology, we also review the most recent developments in nano-biosensors for the rapid and early detection of COVID-19. Furthermore, the photothermal/bioimaging response of single-chirality is reviewed in order to enhance the cytotoxicity of drugs against cancer cells over simple carbon nanotubes (CNTs). The single-chirality allows for precise imaging (due to efficient absorption and emission) of tumors/blood vessels up to ∼10-fold higher by injecting a low dose. We hope this review stimulates further study on single-chirality controlled SWCNTs for practical applications. [ABSTRACT FROM AUTHOR]

Expression of concern for 'Surface modification engineering of two-dimensional titanium carbide for efficient synergistic multitherapy of breast cancer' by Lei Bai et al., J. Mater. Chem. B, 2020, 8, 6402–6417, https://doi.org/10.1039/D0TB01084G. [ABSTRACT FROM AUTHOR]

For most cancers, multimodal cancer synergistic therapy is far more effective than monotherapy. Herein, a multifunctional nanocarrier based on lentinan (LTN) in situ functionalized molybdenum disulfide nanoflowers (MoS2@LTN NFs) is developed by a simple hydrothermal method together with the in situ surface modification strategy. We utilized them to load chemotherapeutic drug gemcitabine (GEM) for in vitro and in vivo chemo-photothermal (Chemo-PTT) therapy. The results show that MoS2@LTN NFs have the following characteristics: (1) the in situ encapsulated LTN can affect the crystal structure of MoS2, and the light absorption capacity of MoS2@LTN is 1.26 times higher than that of pure MoS2; (2) it could achieve different drug release behaviors by dual stimulation with acidic pH and NIR laser irradiation; (3) in vivo experiments demonstrated that synergistic Chemo-PTT therapy achieved by using MoS2@LTN-GEM has a more favorable therapeutic effect than monotherapy. Accordingly, MoS2@LTN NFs could be developed as promising nanocarriers for synergistic therapy. [ABSTRACT FROM AUTHOR]

By delivering the idea of green and safe hydrogen energy and novel photothermal therapy to the biomedical field, engineering of therapeutic nanomaterials for treatment of major diseases (such as cancer) holds great significance. In this work, a novel PdMo bimetallene was synthesized by a solvothermal reduction method, and it was explored and applied in the field of anti-tumor therapy for the first time. The absorption peak of the PdMo bimetallene can be precisely adjusted in the NIR biological window (700–1350 nm) only by changing the synthesis time. At the same time, it also shows strong light absorption and high photothermal conversion efficiency. Specifically, the photothermal conversion efficiencies at 808 nm, 980 nm and 1064 nm are 43.1%, 51.7% and 69.15%, respectively. Surprisingly, a PdMo bimetallene is an efficient catalyst, which can effectively promote hydrogen production from the hydrolysis of ammonia borane (AB) under acidic and photothermal conditions. Benefitting from these excellent properties, a multifunctional composite nano therapeutic agent (PdMo@AB@HA) was developed via layer-by-layer surface modification with AB and hyaluronic acid (HA). In this way, the synergistic PTT/hydrogen therapy of PdMo@AB@HA composite nanosheets in the NIR-I and NIR-II windows (808 nm, 980 nm, and 1064 nm) on mouse tumor xenografts of different depths was realized. Furthermore, the controlled release of hydrogen, targeted endocytosis, efficient eradication of tumors of different depths and high biosafety were systematically proved in vitro and in vivo. This work not only provides a novel and efficient theranostic nanoplatform for efficient cancer theranostics, but also provides a new strategy for the development of safe and efficient new anti-tumor therapies. [ABSTRACT FROM AUTHOR]

Cancer is a leading cause of human mortality. Given that it is difficult for conventional therapeutic approaches to effectively eradicate tumors and inhibit their recurrence and metastasis, new therapeutic strategies for solving this problem are urgently needed. In this work, we report the development of a two-dimensional titanium carbide nanocomposite drug delivery system. The system can be used for the synergistic treatment of tumors through photothermal/photodynamic/chemotherapy and can also inhibit tumor recurrence and metastasis by activating the immune system. A surface modification engineering strategy has been elaborately designed to realize the multifunctionalization of an MXene, Ti3C2. In this strategy, the nanocomposite drug delivery system (Ti3C2@Met@CP) was established via layer by layer adsorption of metformin (Met) and compound polysaccharide (CP) on the surface of Ti3C2 nanosheets. Among these materials, the synthesized (AlOH)4−-functionalized Ti3C2 nanosheets possess strong near-infrared absorption (extinction coefficient of 36.2 L g−1 cm−1), high photothermal conversion efficiency (∼59.6%) and effective singlet oxygen generation (1O2). Compound polysaccharide (CP) is a new immunomodulator formed by mixing lentinan, pachymaran and tremella polysaccharides in optimal proportions. Especially, the decoration of CP onto the Ti3C2 nanosheets endows Ti3C2 with a well-defined shell, improves its tumor site aggregation and biocompatibility, and activates the host's immune functions. The synergistic eradication and inhibition of tumor recurrence and metastasis have been systematically evaluated by in vivo and in vitro experiments. [ABSTRACT FROM AUTHOR]

The energy level alignment and carrier mobility of the charge transport layer are of crucial importance for electron extraction and transport in planar heterojunction perovskite solar cells (PSCs). In this work, a carbon nitride modified SnO2 nanocomposite, SnO2/graphitic carbon nitride (g-C3N4) quantum dots, was designed as the functional electron transport layer (ETL) to precisely regulate the interfacial charge dynamics for high-performance PSCs. It is demonstrated that the g-C3N4 could recast the electronic density distribution around the neighboring SnO2 crystal unit, thus effectively eliminating the oxygen-vacancy-reduced trap centers and promoting the interface and bulk electron transport. Consequently, this carbon nitride modified SnO2 nanocomposite exhibits appropriate electrical properties including suitable energy level alignment and high conductivity. Employing the typical hybrid SnO2-based ETL, a maximum power conversion efficiency (PCE) of 22.13% (Voc = 1.176 V, Jsc = 24.03 mA cm−2, FF = 0.783) can be achieved for planar heterojunction PSCs, with negligible hysteresis and long-term stability (only 10% PCE decay after 1500 h at a relative humidity of 60%). Our work offers a hybrid ETL design strategy to improve the efficiency and stability of PSCs. [ABSTRACT FROM AUTHOR]

Ligand-assisted interface engineering has been considered as a promising strategy to improve the performance and stability of perovskite solar cells (PSCs) simultaneously. Due to the insulating properties of conventional non-conjugated ligands, trap passivation is always at the expense of the interface/bulk carrier transport of the perovskite film. To overcome this paradox, a functional organic amine salt, 3-phenyl-2-propen-1-amine iodide, (PPEAI), is introduced to modify the interfacial characteristics of perovskite films via an “interfacial stitching effect”. This typical ligand could effectively contribute to the suppression of surface defects and ion migration. Furthermore, improved charge transport behavior of perovskite films can be achieved due to the conjugation and delocalization characteristics of PPEAI. By employing the optimized PPEAI modified perovskite film, a 21.01% efficiency was obtained from the champion device, with good stability under both ambient conditions and operation conditions without encapsulation. [ABSTRACT FROM AUTHOR]

The frequency of oil spills and the increasing amount of oily sewage not only cause serious water pollution as well as a lot of ecological problems but also result in huge economic losses. To address such problems, developing advanced technologies and materials for achieving efficient oil/water separation is a critical way and emerging as a hot research topic nowadays. Herein, we have reviewed the recent developments in oil/water separation by using superwetting porous materials, mainly focusing on natural materials. By using natural materials as examples, we show how to use superwetting porous materials to separate different mixtures of water and oil, including the inherent superwettability of the natural materials, separating method/process, and separation mechanism. Natural superwetting materials are usually low-cost and eco-friendly, and can be easily obtained, so oil/water separation based on natural materials has great promise to address the above-mentioned globally recognized oil contamination challenge. In addition, these natural examples seem more attractive to the general researcher who is new to this field as well as the expert and even the public, since natural materials look more interesting than artificial complex materials. We believe our review will help beginners better understand the significance, application value, mechanism and principle of oil/water separation by superwetting porous materials. [ABSTRACT FROM AUTHOR]

Organic gain materials are highly attractive for lasing due to their chemical tunability and large stimulated emission cross sections. In previous reports, the radiative decay rate kr was considered as an important factor to determine outstanding amplified spontaneous emission (ASE) performance of organic molecules. In this study, we use quantum mechanics to reveal the influential factors on photophysical properties of organic emitters, and give insight into the effect of kr on ASE performance. Based on the theoretical analysis of three molecules with similar structure, calculated results show that large kr derives from enhanced transition density ρ between the electronic wave functions of the ground-state and the lowest excited singlet state as well as a handful of low-frequency torsional modes with small Huang–Rhys factor S, further, kr values are calculated depending on molecular vibration terms. In addition, through the analysis of non-radiative decay rate knr considering vibration terms (vibronic coupling constants), the comparison of kr and knr shows that the radiative decay process is promoted in the three molecules. The two aspects are desired for outstanding ASE performance. Our work shows that the roles of transition density and vibrational modes are crucial to clarify the photophysical properties, which govern the ASE performance in organic light emitters. [ABSTRACT FROM AUTHOR]

In this article, an inorganic–organic bilayer hole transport layer (B-HTL) is designed and utilized in planar perovskite solar cells. Here the B-HTL consists of an inorganic VOx matrix and a copper phthalocyanine (CuPc) buffer layer, providing excellent resistance to moisture as well as the alignment of the interfacial energy level. Benefiting from this typical HTL, an enlarged built-in potential and charge extraction can be achieved in PSCs simultaneously. Correspondingly, a champion device with a B-HTL shows a 16.85% efficiency with negligible hysteresis, which is superior to that of a PSC based on a PEDOT:PSS HTL. Meanwhile, significantly prolonged stability of the PSC with the B-HTL can be observed, exhibiting only a 10% efficiency loss after 350 hours in ambient air. Moreover, such an entirely low-temperature (≤60 °C) fabrication process of this typical PSC exhibits its successful application in flexible devices. [ABSTRACT FROM AUTHOR]

A simple achievement of six different super-wettabilities on the femtosecond laser ablated polydimethylsiloxane (PDMS) surface is reported for the first time. Both the experimental and theoretical analysis revealed that underwater oil wettability and underwater bubbles' behavior on a solid surface are closely related to the in-air water wettability of the substrate surface. The original femtosecond laser-induced microstructured PDMS surface exhibited excellent superhydrophobicity in air and generally became superoleophilic and superaerophilic in water. After being further irradiated by oxygen plasma, the rough PDMS surface switched to superhydrophilic. Underwater superoleophobicity and superaerophobicity could be exhibited when such a superhydrophilic PDMS surface was immersed in water. Furthermore, various superhydrophobic–superhydrophilic, underwater superoleophobic–superoleophilic and underwater superaerophobic–superaerophilic hybrid patterns were successfully designed and achieved on the femtosecond laser ablated PDMS surface by subsequent selective oxygen plasma treatment. We believe that the reported preparation principle of superhydrophobic, superhydrophilic, underwater superoleophobic, underwater superoleophilic, underwater superaerophobic, and underwater superaerophilic surfaces would have important guiding significance to researchers and engineers to effectively control water droplets, oil droplets and the behavior of bubbles on a material surface. [ABSTRACT FROM AUTHOR]

Superoleophobicity is a phenomenon where the contact angles of various oil droplets with low surface tension on a solid surface are larger than 150°. In the past few years, there has been much growing interest in the design and application of superoleophobic surfaces. Such surfaces have great significance for both fundamental research and a variety of practical applications, including oil-repellent coatings, self-cleaning, oil/water separation, oil droplet manipulation, chemical shielding, anti-blocking, designing liquid microlens, oil capture, bioadhesion, guiding oil movement and floating on oil. Herein, we systematically summarize the recent developments of superoleophobic surfaces. This review focuses on the design, fabrication, characteristics, functions, and important applications of various superoleophobic surfaces. Although many significant advances have been achieved, superoleophobic surfaces are still in their “toddler stage” of development. The current challenges and future prospects of this fast-growing field of superoleophobicity are discussed. [ABSTRACT FROM AUTHOR]

Metallic films are widely used in many micro-cavities or as electrodes. However, the quenching of fluorescent molecules and the large absorption loss of metallic films are generally considered fatal for lasing. In this article, we present the enhanced lasing of an organic gain medium in a planar waveguide, assisted by the plasmonic hybrid structure of an Ag nanoparticles (NPs)–Ag film. Compared to the devices of gain media deposited on glass, Ag film, and Ag NPs island film, the lowest lasing threshold was achieved by the gain medium deposited on the Ag NPs–Ag film hybrid structure. This is attributed to the hybrid plasmonic coupling between the localized surface plasmons of Ag NPs and the delocalized surface plasmon polariton of the Ag film, leading a more intense localized electric field. In addition, the reinjection and confinement of the leaking photons into the gain medium by the external feedback of the Ag film also contributes to the enhanced lasing. Our results could provide us with a unique approach to effectively avoid the negative effect of the metallic film, enhance the lasing gain of organic dye molecules, and realize a lower pumped threshold and stronger lasing. [ABSTRACT FROM AUTHOR]

Ultrasmooth perovskite thin films are prepared by a solution-based one-step micro-flowing anti-solvent deposition (MAD) method carried out in air with simplicity and practicability. Engaging inert gas blow and anti-solvent drips as accelerators, ultrafast crystallizing, thickness controllable, and high quality methylammonium lead iodide films are prepared with a least root mean square roughness of 1.43 nm (1.95 nm on average), achieving the smoothest surface morphology to the best of our knowledge, as well as a rather compact perovskite layer with a high coverage ratio. Perovskite films formed from MAD require no annealing procedure to ultimately crystallize, realizing a very fast crystallizing procedure within few seconds. By controlling the thickness of perovskite films, superior photovoltaic performance of solar cells with a large fill factor of 0.8 and a PCE of 15.98% is achieved without a glovebox. MAD technology will benefit not only highly efficient photovoltaic devices, but also perovskite-based hybrid optoelectronic devices with field effect transistors and light emitting diodes as well. [ABSTRACT FROM AUTHOR]

Organic optical gain materials are the basis for organic solid-state lasers. However, the fundamental mechanism for Amplified Spontaneous Emission (ASE) is absent. Herein, three star-shaped molecules based on a truxene core with π-conjugated arms are studied to illuminate the influence of the molecular structure on ASE performance. We found that the three compounds demonstrated different ASE characteristics. The strong conjugated linkage in the molecular arms enhanced ASE, while the attenuated conjugated linkage deteriorates ASE for the given molecular structures. Based on the theoretical analysis, the conjugative coupling suppresses the low-frequency vibration, which is beneficial to the formation of an effective “four-level” energy system for ASE. On the contrary, the poor conjugative coupling brings out a mass of low-frequency modes, and hence, continuous vibronic energy sublevels will ruin the molecular “four-level” energy system. Our study presented a clear picture to clarify the ASE mechanism and offers valuable guidance for the design of new organic optical gain materials. [ABSTRACT FROM AUTHOR]

A simple and one-step method to form a rough ZnO layer consisting of micro/nanoscale hierarchical structures via direct femtosecond laser ablation of the Zn surface is reported for the first time. The resultant surfaces show switchable wettability between superhydrophobicity and quasi-superhydrophilicity via alternate UV irradiation and dark storage. [ABSTRACT FROM AUTHOR]

Switchable underwater superoleophobicity–superoleophilicity on femtosecond laser-induced rough TiO2 surfaces by alternate UV irradiation and dark storage is achieved for the first time. Femtosecond laser ablation not only forms a micro/nanoscale hierarchical rough structure but also oxidizes the Ti materials, resulting in a rough TiO2 layer covering on the surface. The reversible switching of underwater oil wettability is caused by photoinduced switching between superhydrophobic and superhydrophilic states in air. These rough TiO2 surfaces can even respond to visible light. We believe this subtle switching method will be potentially applied in the biological and medical fields. [ABSTRACT FROM AUTHOR]

A highly-efficient inverted heterojunction perovskite solar cell was prepared. A homogeneous and compact perovskite (CH3NH3PbI3) layer was prepared via a two-step solution deposition method, and subsequently a double-layer PCBM film was deposited by a sequential spin-coating/vapor deposition process as the electron transport layer. The optimised device could achieve a 12.2% (average 11.09%) efficiency. [ABSTRACT FROM AUTHOR]

Reported here is a bioinspired fabrication of transparent underwater superoleophobic and anti-oil surfaces using a femtosecond laser treatment. Rough nanoscale structures were readily created on silica glass surfaces by femtosecond laser-induced ablation. Underwater superoleophobicity and ultralow oil-adhesion were obtained by the rough nanostructures with a wide variation of processing parameters, and the as-prepared surfaces exhibited a high transparency in water. This phenomenon is attributed to the presence of the water environment because scattering and refraction are effectively weakened. As a maskless and cost-effective method, the femtosecond laser processing of transparent materials (glass) may provide a new method to create biomimetic transparent underwater surfaces, allowing for the development of novel underwater anti-oil optical devices. [ABSTRACT FROM AUTHOR]

In this article, Ag-encapsulated Au nanorods (Au@Ag NRs) are prepared and introduced into dye-sensitized solar cells (DSSCs). As a unique plasmonic nanostructure, this composite exhibits the superiorities of enhanced light-harvesting as well as restrained charge recombination of DSSCs. Remarkably, the enhanced light absorption of the photoanode can be obtained via the surface plasmon resonance (SPR) effect of the Au@Ag NRs, whereas a broadened absorption in the red and near-infrared (NIR) region ensures the full utilization of the solar energy. Beyond the dominated optical utility, the presence of the Au@Ag NRs promotes the suppression of the charge recombination, further enhancing the photochemical catalysis of DSSCs. An optimized Au@Ag NR modified DSSC is achieved with a power conversion efficiency of 8.43%, which is significantly superior to that of the pure TiO2 DSSC with a PCE of 5.91%. [ABSTRACT FROM AUTHOR]

We report the electroluminescent (EL) performance of a series of fluorinated 9,9′-bianthracene derivatives (BAnFs) to serve as host materials for selected dopants in organic light-emitting diodes (OLEDs). Different F substitution patterns strongly affect the EL performances. In particular, 10,10′-bis(4-fluorophenyl)-9,9′-bianthracene (BAn-(4)-F) works as an excellent fluorescent host for N,N-diphenylamino phenyl vinyl biphenyl (DPAVBi) and 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]pyrano(6,7,8-ij)quinolizin-11-one (C545T) dopants to obtain high-performance OLEDs with excellent external quantum efficiencies (EQEs) of 5.43% and 5.20%, respectively. We demonstrate that the improved EQEs are due to the enhanced occurrence of singlet excitons in BAn-(4)-F-based EL devices. The BAn-(4)-F host molecule with a particular twisted intramolecular charge-transfer (TICT) excited state, which participates in a charge-transfer (CT) intersystem crossing mechanism, realizes transitions from the triplet to singlet CT-states. At the dopant site, the available singlet excitons formed via Förster energy transfer from host BAn-(4)-F to dopant are greatly increased. We conclude that the BAn-(4)-F host based on 9,9′-bianthracene can significantly enhance the singlet generation fraction in EL devices. [ABSTRACT FROM AUTHOR]

Femtosecond laser microfabrication has been recently utilized in interface science to modify the liquid wettability of solid surfaces. In this paper, a silicon surface with hierarchical micro/nanostructure is fabricated by a femtosecond laser. Similar to fish scales, the laser-induced surface shows superhydrophilicity in air and superoleophobicity underwater. The oil contact angles can reach up to 159.4 ± 1° and 150.3 ± 2°, respectively, for 1,2-dichloroethane and chloroform droplets in water. In addition, the surface exhibits ultralow oil-adhesion. In the oil-water-solid three-phase system, water can be trapped in the hierarchical rough structure and form a repulsive oil layer according to the extended Cassie's theory. The contact area between the as-prepared surface and oil droplets is significantly reduced, resulting in superoleophobicity and ultralow oil-adhesion in water. In addition, as a potential application, the working principle diagram of preventing blockage ability of underwater superoleophobic pipes is propounded. [ABSTRACT FROM AUTHOR]

A series of new fluorinated 9,9′-bianthracene derivatives (BAnFs) have been designed and synthesized to serve as deep-blue dopants in organic electroluminescent (EL) devices. With the different substitution patterns of the electron-withdrawing groups, such as F and CF3, the photophysical properties, the energy levels and thermal stability of these BAnFs are tuned, which are supported by a density functional study of their geometry and electronic structure. In the thin film state, the fluorescent emissions of the BAnFs are fine-tuned from 448 to 439 nm, with varied fluorinated phenyl rings attached to the 9,9′-bianthracene core. All the BAnFs show a considerable thermal stability, which have high Tg values, above 150 °C. A pure blue emission at the Commission Internationale de l'Éclairage (CIE) coordinates (0.156, 0.083), has been achieved using the host 4,4′-bis(N-carbazolyl)biphenyl (CBP) doped with 10,10′-bis(3,5-bis(trifluoromethyl)phenyl)-9,9′-bianthracene (BAn-(3,5)-CF3). The maximum current efficiency and power efficiency of the BAn-(3,5)-CF3-doped device are 3.05 cd A−1 and 2.62 lm W−1, corresponding to 5.02% of the maximum external quantum efficiency. The synthesized new fluorinated 9,9′-bianthracene derivatives show potential applications as highly efficient pure blue emitters for organic light emitting devices. [ABSTRACT FROM AUTHOR]

A mixed halide perovskite of CH3NH3PbI(3-x)Cl(x) is synthesized via two-step sequential solution deposition by using a mixture of PbCl2 and PbI2 as the precursor to overcome the low solubility of pure PbCl2 with easy morphology control. 11.7% power conversion efficiency is achieved for the mesoscopic cell, much higher than the cell constructed via a spin-coating process.