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One of the challenges for high-efficiency single-component-based photoredox catalysts is the low charge transfer and extraction due to the high recombination rate. Here, we demonstrate a strategy to precisely control the charge separation and transport efficiency of the catalytic host by introducing electron or hole extraction interlayers to improve the catalytic efficiency. We use simple and easily available non-conjugated polyelectrolytes (NCPs) (i.e., polyethyleneimine, PEI; poly(allylamine hydrochloride), PAH) to form interlayers, wherein such NCPs consist of the nonconjugated backbone with charge transporting functional groups. Taking CdS as examples, it is shown that although PEI and PAH are insulators and therefore do not have the ability to conduct electricity, they can form good electron or hole transport extraction layers due to the higher charge-transfer kinetics of pendant groups along the backbones, thereby greatly improving the charge transfer capability of CdS. Consequently, the resultant PEI-/PAH-functionalized nanocomposites exhibit significantly enhanced and versatile photoredox catalysis. Conjugated polymers are commonly used as charge conducting systems in photocatalysts, but the use of nonconjugated polymers is less well understood. Here CdS photocatalysts are coated by non-conjugated polyelectrolyte layers, and the influence of the polymer on charge transfer over CdS is explored.

Room-temperature afterglow (RTA) materials with long lifetime have shown tremendous application prospects in many fields. However, there is no general design strategy to construct near-infrared (NIR)-excited multicolor RTA materials. Herein, we report a universal approach based on the efficient radiative energy transfer that supports the reabsorption from upconversion materials (UMs) to carbon dots-based RTA materials (CDAMs). Thus, the afterglow emission (blue, cyan, green, and orange) of various CDAMs can be activated by UMs under the NIR continuous-wave laser excitation. The efficient radiative energy transfer ensured the persistent multicolor afterglow up to 7 s, 6 s, 5 s, and 0.5 s by naked eyes, respectively. Given the unusual afterglow properties, we demonstrated preliminary applications in fingerprint recognition and information security. This work provides a new avenue for the activation of NIR-excited afterglow in CDAMs and will greatly expand the applications of RTA materials.

All-solution-processed multilayered white polymer light-emitting diodes (WPLEDs) are promising candidates for low-cost and large-area flexible full-color flat-panel displays and solid-state lightin...

Porous carbon is highly desired in supercapacitor electrodes due to its high specific surface area, ample pore size and superior electrochemical stability. Yet, the development of a general and simple synthetic method to prepare porous carbon remains challenging. Meanwhile, recycling waste to obtain high value-added materials is an effective way to solve environmental pollution and resource shortage problems. Herein, a general one-step solid-state pyrolysis method is developed to synthesize multi-hierarchical porous carbon using bio-wastes as precursors and potassium ferrate as the pore-forming agent. This method is superior to the traditional two-step or multi-step method due to its simple procedure, low cost, little pollution and time-saving features. The multiple pore-forming effect derived from potassium ferrate is responsible for this multi-hierarchical porous structure. The resulting porous carbon is used to fabricate symmetrical supercapacitors, exhibiting specific capacitances of 291.2 F g−1 at 1 A g−1 and 240.1 F g−1 at 10 A g−1, and exceptional cyclic stability with 93.2% capacitance retention over 100 000 cycles. Furthermore, this method has been applied to five other types of bio-wastes, verifying its universality. In addition, the multiple pore-forming mechanism of potassium ferrate is investigated. This work provides a simple and general method to convert abandoned bio-wastes into ideal supercapacitor electrode materials, which hold great potential in energy storage applications.

Liquid-exfoliated 2D transition metal disulfides (TMDs) are potential substitutes for poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as hole transport layers (HTLs) in Organic Solar Cells (OSCs). Herein, high-yield and high-quality WS2 flake layers are prepared by comprehensively controlling the initial concentration, sonication processing time and centrifugal speed. The WS2 layers deposited on in situ transparent indium tin oxide (ITO) without plasma treatment show higher uniformity and conductivity than that formed on ITO after plasma treatment. With a significant increase in the short-circuit current density (JSC), the power conversion efficiency (PCE) of PM6:Y6-based non-fullerene OSCs using optimized WS2 as the HTL is higher than that using PEDOT:PSS as the HTL(15.75% vs. 15.31%). Combining the morphology characteristics with carrier recombination characteristics, the higher quality of the ITO/WS2 composite substrate leads to better charge transport and a lower bimolecular recombination rate in OSCs, thereby improving the device performance.

Organic solar cells (OSCs) have been considered as a promising, cost-effective alternative to the silicon-based solar cells due to their light weight, mechanical flexibility, and easy fabrication features. Over the past decades, organic semiconducting materials have been developed rapidly for use in bulk heterojunction (BHJ) OSCs. Among them, porphyrin-based small molecules have been widely applied as electron donors and electron acceptors in BHJ OSCs due to their large conjugated planar structures and strong UV-visible and near-infrared absorption. In this short review article, we mainly focus on summarizing the recent progress of the rational design of push–pull porphyrin-based small molecules for BHJ OSC applications. After various structural developments, the power conversion efficiencies (PCEs) of porphyrin-based small molecules as electron donors in OSCs have exceeded 12%. Apart from that, a PCE of 9.6% has been recorded for a device based on a porphyrin electron acceptor. This paper will provide a good insight into the structure–performance correlation and molecular engineering strategies of porphyrin-based small molecules in a stepwise manner.

Using conventional fac-[Ir(C^N)3]-homoleptic or [Ir(C^N)2(L^X)]-bis-heteroleptic iridium(III)-complexes with NIR-phosphorescence (NIR = near infrared) as dopants, the realization of reliable NIR-OLEDs/PLEDs (organic/polymer light-emitting diodes) with high performance remains a real challenge. In this study, taking Hqibt (1-(benzo[b]-thiophen-2-yl)-isoquinoline) as the HC^N1 ligand, Hppy (phenyl-4-yl)pyridine) as the HC^N2 ligand and Br-Hpic (5-Br-picolinic acid) or Hpic (picolinic acid) as the N^O-ancillary, two novel C1-symmetric [Ir(C^N1)(C^N2)(N^O)]-tris-heteroleptic iridium(III)-complexes [Ir(iqbt)(ppy)(pic)] (1) and [Ir(iqbt)(ppy)(Br-pic)] (2) are molecularly designed, respectively, where large TDM (transition dipole moment) and strengthened 3MLCT (metal-to-ligand charge transfer) effects are established to afford their good NIR-phosphorescent efficiency (ΦPL = 0.27 for 1 (λem = 698 nm); 0.21 for 2 (λem = 696 nm)). Moreover, in their doped EMLs (emitting layers), a preferentially horizontal orientation of the TDMs is promoted, due to which, the NIR-PLEDs-1–2 exhibit an attractively high efficiency (ηmaxEQE = 3.1–4.7%; λem = 698 nm) as well as an almost negligible (

In this paper, we demonstrate a solution-processed MoSe2 quantum dots/PEDOT:PSS bilayer hole extraction layer (HEL) for non-fullerene organic solar cells (OSCs). It is found that the introduction of MoSe2 QDs can alter the work function and phase separation of PEDOT:PSS, thus affecting the morphology of the active layer and improving the performance of OSCs. The MoSe2 QDs/PEDOT:PSS bilayer HEL can improve the fill factor (FF), short-circuit current density (Jsc) and power conversion efficiency (PCE) of OSCs based on different active layers. The best PCE of up to 17.08% was achieved based on a recently reported active layer binary system named SZ2:N3, which is among the highest reported values to date for OSCs using 2D materials as an interface modifier. Our study indicates that this simple and solution-processed MoSe2 QDs/PEDOT:PSS bilayer thin film could be a potential alternative HEL to the commonly used PEDOT:PSS conducting polymers.

Based on geometrical isomerisation of [Ir(C^N1)(C^N2)((N^O))]-tris-heteroleptic Ir(iii)-complexes, the augmented transition dipole transition (TMD) with a preferential horizontal orientation, which is beneficial for their NIR-phosphorescence, is reported.

Despite the cost-effective and large-area scalable advantages of NIR-PLEDs based on iridium(III)-complex-doped polymers, the intrinsic phase-separation issue leading to inferior device performance is difficult to address. In this study, taking the vinyl-functionalized [Ir(iqbt)2(vb-ppy)] (Hqibt = 1-(benzo[b]-thiophen-2-yl)-isoquinoline; vb-Hppy = 2-(4′-vinylbiphenyl-4-yl)pyridine) as the polymerized complex monomer, two series of Ir(III)-complex-grafted polymers Poly(NVK-co-[Ir(iqbt)2(vb-ppy)]) and Poly((vinyl-PBD)-co-NVK-co-[Ir(iqbt)2(vb-ppy)]) (NVK = N-vinyl-carbazole; vinyl-PBD = 2-(4-(tert-butyl)phenyl)-5-(4′-vinyl-[1,1′-biphenyl]-4-yl)-2,5-dihydro-1,3,4-oxadiazole) are obtained, respectively. Moreover, by using the bipolar Ir(III)-complex-grafted polymer further doped or grafted with an electron-transport unit as the emitting layer (EML), reliable NIR-PLEDs are realized. In particular based on the concurrent covalent-linkages of both the Ir(III)-complex and the vinyl-PBD towards the carrier-balanced NIR-PLED-III, the achievement of an almost negligible (

Despite the domination of conventional [Ir(C^N)2(L^X)]-bis-heteroleptic iridium(III)-complexes with NIR-phosphorescence (NIR = near-infrared) as dopants for reliable NIR-OLEDs/PLEDs (organic/polymer light-emitting diodes), the achievement of high performance remains a real challenge. In this study, taking Hiqbt (1-(benzo[b]-thiophen-2-yl)-isoquinoline) as the C^N ligand and one of the asymmetric Schiff-base ligands with different electronic effects as the N^O-ancillary ligand, three novel C1-symmetric [Ir(C^N)2(N^O)]-bis-heteroleptic iridium(III)-complexes 1–3 were developed. With contributions from the TDM (transition dipole moment) and the emitting dipole orientation induced by the N^O-ancillary electronic effects, the doped NIR-PLEDs-1–3 exhibited attractive high efficiency (ηmaxEQE = 3.3–5.6%; λem = 708–712 nm) apart from the almost negligible (

Developing organic single molecule white light emitters (SMWLE) with high luminescence efficiency, ultra-long phosphorescence (ULP) and excitation-dependent (ED) color-tunable emission is intriguing and highly desirable from theoretical research to practical application. Nevertheless, it is an extremely challenging topic. Here, it is found that three simple terpyridine-based derivatives (P1, P2 and P3) could exhibit unusual multiple emissions and interesting color-tunable emissions. In particular, P3 as the first example could simultaneously achieve bright white light emission with high quantum yield (49%), ultra-long phosphorescence (τ = 0.57 s) and ED color-tunable emission under ambient conditions. Accordingly, it can achieve novel multicolor emission including yellowish green light, white light, blue light, bluish green light and red phosphorescence light in a very wide wavelength range. Both experimental and theoretical studies reveal that such novel emission characteristics are due to the fact that P3 integrates monomer, excimer, and intermolecular charge transfer (ICT) triple-mode emissions in the crystalline state. These results provide a rational strategy for the construction of SMWLE and ED color-tunable emission materials. Moreover, such simple multifunctional materials would show huge potential in displays, anti-counterfeiting, and so on.

It is known that the use of magnesium doped zinc oxide (ZnMgO) nanoparticles results in a serious exciton quenching and unbalanced charge carriers inside the quantum dot light-emitting diodes (QLEDs), leading to an inferior device performance (particularly in blue QLEDs). Herein, we use water as a passivation agent to fix the interface between QDs and ZnMgO. On the one hand, the oxygen atoms in water could contact with metal atoms through an electrostatic interaction to fill the oxygen vacancies on the surface of ZnMgO and remove the surface defects so that the excitons formed inside QDs are less quenched. On the other hand, it slightly decreases the electron transport from ZnMgO to QDs, resulting in much more balanced holes and electrons inside the QD emissive layers. Therefore, the blue QLEDs made by the water-passivated ZnMgO exihibit an improved external quantum efficiency (EQE) of 11.0% and luminance of over 20 000 cd m−2 at 6 V, which is significantly higher than those of blue QLEDs made by pristine ZnMgO. To further understand the improved performance among the blue QLEDs, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize these water-passivated ZnMgO nanoparticles.

Iridium-based polymer PM6Ir1 as an electron donor and two nonfullerene materials N3 and ITIC-Th as electron acceptors were selected to prepare efficient polymer solar cells (PSCs). ITIC-Th was used as the third component to enhance photon harvesting and as a morphology regulator to optimize molecular arrangement and phase separation in the ternary active layer. Improvements in open circuit voltage (0.86 V vs. 0.84 V), short circuit current density (26.53 mA cm−2vs. 26.13 mA cm−2) and fill factor (75.47% vs. 74.11%) are simultaneously obtained for the PSCs with 10 wt% ITIC-Th in the acceptor mixture, leading to a power conversion efficiency (PCE) enhancement from 16.27% to 17.22%. The charge mobility and charge transport balance in the ternary active layer can be enhanced by incorporating ITIC-Th, resulting from the optimized phase separation and molecular arrangement with ITIC-Th as a morphology regulator. The positive effect of ITIC-Th incorporation on PCE improvement can be demonstrated by the relatively high external quantum efficiency values of the optimal ternary PSCs in the spectral range from 300 to 820 nm.

2,1,3-Benzothiadiazole (BT) and its derivatives are very important acceptor units used in the development of photoluminescent compounds and are applicable for the molecular construction of organic light-emitting diodes, organic solar cells and organic field-effect transistors. Due to their strong electron-withdrawing ability, construction of molecules with the unit core of BT and its derivatives can usually improve the electronic properties of the resulting organic materials. In this contribution, we review the synthesis of various polymers, small molecules and metal complexes with BT and its derivatives and their applications in organic light-emitting diodes. Furthermore, the molecular design rules based on these cores are discussed.

A linear 5,15-di(naphthalimide) substituted porphyrin ZnD(p-NI)PP is facilely self-assembled into nanowires in solid with well-defined morphology through the synergistic π–π stack interactions of b...

Herein, we report novel supermolecular heterojunctions with six kinds of multi-layer core–shell microstructures, which consist of up to three CT complex components that realize programmable fabrication with defined luminescent CT domains and controllable multi-color-emitting properties. A stepwise seeded-growth route was designed using these CT cocrystals as seed and growing units during the process of fabrication where solution-epitaxy growth would occur based on their perfect lattice matching. This rational multi-step synthetic route furnishes a new insight into developing and constructing more sophisticated organic heterogeneous materials.

It is one of the most difficult and challenging targets to achieve blue phosphorescent organic light-emitting diodes. Herein, we employ tetrafluorinated 2-phenylpyridine (F4ppy) as a cyclometalated ligand, in which the tetrafluorophenyl group contributes to the stabilization of the highest occupied molecular orbital (HOMO) of its iridium(III) complex. Meanwhile, N-heterocyclic carbene (NHC) and acidic pyrazolyl-pyridine (fppz) moieties as ancillary ligands are used to keep the lowest unoccupied molecular orbitals (LUMOs) of the phosphors relatively unchanged. Therefore, the energy gap between the HOMO and LUMO is enlarged and two sky blue emissive iridium(III) phosphors, named (F4ppy)2Ir(CF3-pei) (Ir-1) and (F4ppy)2Ir(fppz) (Ir-2), are achieved. Strong phosphorescent emission at a wavelength of around 460 nm with a photoluminescence quantum yield of around 60% is observed in solution for these two phosphors. Moreover, the organic light-emitting devices made from Ir-1 and Ir-2 exhibit high-efficiencies, affording peak current efficiencies (CEs) of 47.6 and 45.5 cd A−1 with external quantum efficiencies (EQEs) of 20.6% and 19.6%, respectively.

Perovskite solar cells (PSCs) have attracted widespread and intense interest because of their excellent device performance. However, the existence of poor interface contacts and energy losses in the device are key challenges for the development of PSCs in the future. In this work, we developed a novel perylene diimide-based zwitterion (QAPDI) as a cathode interlayer to improve the device performance of inverted PSCs. QAPDI exhibits excellent solubility, appropriate energy levels, and high electron mobility, suggesting that it is a suitable interlayer engineering material in inverted PSCs. The use of QAPDI as a cathode interlayer between the PCBM layer and metal electrode could improve the interface contact and reduce the energy level barrier, thus facilitating efficient electron injection and transport. Moreover, the application of QAPDI could obstruct the permeation of moisture into the perovskite film to reform the device stability. As a consequence, the optimal QAPDI-based device efficiency reached 20.55% together with enhanced device stability compared with that of the control device (18.6%). This work provides an excellent alternative cathode interlayer material for high-performance inverted PSCs.

The photophysical properties of two previously synthesized, highly efficient, bright red emitting complexes [Eu(btfa)3DPEPO] (CIE, 0.672; 0.326) (Eu-1) and [Eu(nta)3DPEPO] (CIE, 0.673; 0.326) (Eu-2) (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, nta = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide) are reported. The complexes have been used as dopants to fabricate several single and double emitting layer (EML) electroluminescent (EL) devices. At the optimum doping concentration of 4 wt%, the single EML device of Eu-1 exhibited a pure red color with an external quantum efficiency (EQE) of 2.9% and a maximum brightness (B) = 1320 cd m−2, maximum current efficiency (ηc) = 4.08 cd A−1, maximum power efficiency (ηp) = 3.37 lm W−1 with a very low turn-on voltage (Vturn-on) = 3.8 V. Importantly, the single EML device of Eu-2 at the optimum doping concentration exhibited pure red EL with EQE of 6.0% with the best EL performance: B = 2108 cd m−2, ηc = 8.45 cd A−1, and ηp = 6.98 lm W−1 at a very low Vturn-on = 3.5 V. The performances of this device are among the best reported for devices incorporating a europium complex as a red emitter. Furthermore, the EL performances were achieved at the current density of 10 mA cm−2, thereby alleviating a serious efficiency roll-off as a major obstacle to the development of Eu-complex based EL devices.

Highly emissive copper(I) halide nanoclusters showing thermally activated delayed fluorescence (TADF) have been paid much attention, but rarely reported so far. Herein, a hexanuclear copper(I) iodide cluster containing a tridentate N∧P∧N ligand, [Cu6I6(ppda)2] {ppda = 2-[2-(dimethylamino)phenyl(phenyl)phosphino]-N,N-dimethylaniline}, was synthesized. All six copper atoms are four-coordinate, including four CuPNI2 and two CuI4 units. This complex exhibits intense white emission in the powder state at room temperature and shows a peak at a wavelength of 535 nm (ΦPL = 0.36) with a microsecond lifetime (τ = 4.4 μs). Emission colors can be largely tuned from blue to white to yellow, from the crystal to powder to film state at 297 K. The emission of [Cu6I6(ppda)2] originates from a combination of MLCT and XLCT transitions. This complex showed good thermal stability. A solution-processed, nondoped device of complex [Cu6I6(ppda)2] exhibits stable yellow emission with the CIE coordinates (x, y) of (0.43, 0.51). [Cu6I6(ppda)2] also shows reasonable photocatalytic H2 evolution activity under visible-light irradiation.

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.

A new homodinuclear complex [Eu(btfa)3]2bpm (1) was synthesized incorporating 4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) as the primary and 2,2′-bipyrimidine (bpm) as the auxiliary ligand. The complex was characterized by analytical and spectroscopic techniques, with special emphasis on the crystal structure and photoluminescence (PL) properties, both experimentally and theoretically. Single crystal X-ray diffraction (SCXRD) analysis reveals that the two Eu(III) ions in 1 are eight coordinate, where the bpm behaves as a N4 donor linking the two Eu(III) ions symmetrically. Each Eu(III) ion displays a distorted square antiprismatic (DSAP, D4d) coordination geometry. Complex 1 displayed bright red emission with (CIE)x,y color coordinates = 0.670; 0.330 and an absolute photoluminescence quantum yield (PLQY) of 54.4%. The theoretical intensity parameters (Ω2 and Ω4), radiative (AR) and non-radiative (ANR) decay rates, intrinsic quantum yield (QEuEu), sensitization efficiency (ηsen) and PLQY were assessed using the LUMPAC software and showed very good agreement with the experimental values. Based on these, an energy transfer (ET) mechanism is proposed and discussed. Moreover, 1 was used as an emitter to fabricate single- and double-emitting layer (EML) red-emitting electroluminescent devices. Double-EML device at the optimum doping concentration of 4.0 wt% displayed impressive EL performances, brightness (B) = 812 cd m−2, maximum current efficiency (ηc) = 3.97 cd A−1, maximum power efficiency (ηp) = 3.89 lm W−1, and external quantum efficiency (EQE) = 2.8% at very low Vturn-on = 3.2 V with (CIE)x,y = 0.662, 0.321 which is close to the standard red color recommended by NTSC (0.67, 0.33).

A surface-modification layer is important for the performance and stability of perovskite solar cells, but the research on surface-modification materials is still lagging behind perovskite materials in the photovoltaic field. In this work, a linear conjugated tetramer, IDTT4PDI, was developed through Stille coupling with a high synthetic yield. IDTT4PDI showed excellent solubility, thermal stability, a suitable LUMO level (−4.08 eV), and high electron mobility, implying that it would be suitable for use as a surface-modification layer in inverted perovskite solar cells. The use of IDTT4PDI as a surface-modification layer improved the interfacial contact between the perovskite layer and PCBM film, reduced the trap-assisted recombination, and enhanced the electron transport efficiency. As a result, an efficiency of over 20% is achieved by an IDTT4PDI-modified MAPbI3 perovskite inverted device, which is much higher than that of the control device (17%). This work opens up a new direction for the use of linear perylene diimide derivatives as efficient surface-modification materials for achieving high-efficiency perovskite solar cells.

Three donor–acceptor–donor type emitters of 2TPA-BT, 2MeTPA-BT and 2DMeTPA-BT were synthesized. Crystal structures for all compounds were determined by single-crystal X-ray diffraction analysis, showing that by introducing one or two methyl groups between the donors and acceptor, the spatial configuration changes greatly for 2MeTPA-BT and 2DMeTPA-BT compared to their parent compound 2TPA-BT. Density functional theory analysis reveals that the emission of 2MeTPA-BT has a more obvious hybridized local and charge-transfer (HLCT) feature based on the influence of steric hindrance of methyl substituents. Attributed to their different spatial configurations and luminescence mechanisms, different emission wavelengths with high photoluminescence quantum yields (ΦPLs) of 75.43%, 93.43% and 89.63% in toluene solvent, as well as 44.76%, 52.19 and 33.87% in neat film, were observed for 2TPA-BT, 2MeTPA-BT and 2DMeTPA-BT, respectively. Furthermore, strong electroluminescence was observed with the emission peaks at 602, 560 and 544 nm, maximum current efficiencies of 11.05 cd A−1, 30.40 cd A−1 and 25.02 cd A−1, maximum power efficiencies of 6.01 lm W−1, 23.67 lm W−1 and 20.37 lm W−1, and maximum external quantum efficiencies of 4.43%, 8.47% and 7.29% for 2TPA-BT, 2MeTPA-BT and 2DMeTPA-BT doped organic light-emitting devices (OLEDs), respectively. This work clearly illustrates the effect of spatial configuration changes on the luminescence properties of organic emitters.

Synthetic materials and biomaterials with elastic moduli lower than 10 MPa are generally considered as soft materials. Research studies on soft materials have been boosted due to their intriguing features such as light-weight, low modulus, stretchability, and a diverse range of functions including sensing, actuating, insulating and transporting. They are ideal materials for applications in smart textiles, flexible devices and wearable electronics. On the other hand, benefiting from the advances in materials science and chemistry, novel soft materials with tailored properties and functions could be prepared to fulfil the specific requirements. In this review, the current progress of soft materials, ranging from materials design, preparation and application are critically summarized based on three categories, namely gels, foams and elastomers. The chemical, physical and electrical properties and the applications are elaborated. This review aims to provide a comprehensive overview of soft materials to researchers in different disciplines.

Thanks to the straightforward white light of single grafting-type polymers based on earth-abundant Zn(ii)-complexes, producing cost-effective flexible WOLEDs/WPLEDs with good device performance remains a formidable challenge. Herein, by using the polymer Poly(NVK-co-[Zn2(MP)3(OAc)]) with excellent physical properties for single-layer WPLEDs, record-high efficiencies (ηMaxc = 13.0 cd A−1, ηMaxp = 6.1 lm W−1 and ηMaxEQE = 9.2%) and low (ca. 25%) efficiency roll-off compared to previous organo-Zn2+-based WOLEDs/WPLEDs are realized. This finding renders single Zn(ii)-complex-grafted polymers a new route to low-cost and large-area flexible WPLEDs for potential full-colour flat displays., Using [Zn2(MP)3(OAc)]-grafted polymer as a single emitting layer, record-high efficiencies and weak (ca. 25%) efficiency roll-off are realized for cost-effective and large-area flexible WPLEDs.

The stable sandwich structure and the excellent redox activity of ferrocene make it a ubiquitous component in organometallic systems. The introduction of a ferrocenyl unit into a polymer skeleton provides a good avenue towards novel materials for various applications in redox batteries, enantioselective catalysis, optical and magnetic switches, etc. Herein, we report a strategic design and synthesis of new ferrocene-based hyperbranched polymers, and demonstrate promising methods for their morphology control as spheres by direct coupling reactions and hollow polyhedra by a templating approach. Furthermore, task-specific applications targeted for their respective architectures are investigated in lithium ion batteries (LIBs) and water treatment, respectively. The spherical polymer used as an electroactive anode in LIBs has a high capacity of 755.2 mA h g−1, stable chargeable performance of over 200 cycles and superior rate capability. For comparison, the hollow counterpart shows a sharp increase of the specific surface area in the precursor-derived magnetic ceramics from 417 to 1195 m2 g−1, and the as-made material exhibits great potential for the rapid removal of trace amounts of pollutants in water with magnetic reusability.

Two new octa-coordinated ternary europium(III) complexes of the type [Eu(btfa)3(Br2-bpy)] (Eu-1) and [Eu(btfa)3(PhE2-bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, Br2-bpy = 5,5′-dibromo-2,2′-bipyridine, PhE2-bpy 5,5′-bis(phenylethynyl)-2,2′-bipyridine) together with a previously reported complex [Eu(btfa)3(bpy)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs).

To develop high-efficiency polymer solar cells (PSCs), the acceptors in a bulk heterojunction (BHJ) blend are supposed to possess complementary absorption bands in the near-infrared region and a suitable energy level to be well-matched with the donors. In this work, a new small molecular acceptor (SMA) named IDTT8-N based on an indacenodithienothiophene (IDTT) core was designed and synthesized. In comparison to the counterpart molecule IDTN with an indacenodithiophene (IDT) core, IDTT8-N with the extended π-conjugation length of an IDT core not only exhibits a red shift of ca. 35 nm in optical absorption but also has little change on its lowest unoccupied molecular orbital (LUMO) energy level. Therefore, PSCs based on PM6:IDTT8-N exhibit a superior short-circuit current density (Jsc) and high open-circuit voltage (Voc). Moreover, apart from the strong face-on molecular stacking, distinct end-group π-πstacking of IDTT8-N can be observed in the blends, facilitating the charge transport. Therefore, the optimized PM6:IDTT8-N-based devices exhibit dramatically high and balanced electron mobility (μe) and hole mobility (μh), whose magnitudes are over 10-3 cm2 V-1 s-1. Consequently, an extraordinary PCE of 14.1% with a relatively high Jsc of 20.98 mA cm-2 and a Voc of 0.94 V was recorded. To our knowledge, it is the new record among PSCs with a SMA based on 2-(3-oxocyclopentylidene)malononitrile (INCN) as end groups. These results indicate that extending the π-conjugation length of the fused ring core of a SMA is an efficient method to both enhance the absorption and the molecular interaction of the acceptor as well as the photovoltaic performance of PSCs.

The exploration of efficient yellow emitters featuring broad emission band plays an essential role for the complementary‐color‐based white organic light‐emitting devices (OLEDs). Herein, two new yellow ionic iridium(III) complexes (Ir1 and Ir2) having excellent sublimation ability are designed and prepared by the incorporation of chlorine‐modified 2‐phenylquinoline ligand and introduction of bulky counter ion. At room temperature, these ionic iridium(III) complexes show bright yellow phosphorescence in both solid and solution states due to the presence of bulky counter ion. They share the same emission wavelength (538 and 573 nm as the emission shoulder) with extremely high quantum yields (as high as 0.91) in Ar‐saturated CH2Cl2. Notably, those complexes also exhibit very broad full width at half maximum (FWHM) (up to 100 nm) attributed to almost the same intensities of emission maximum and shoulder, making them excellent candidates for white electroluminescence. The as‐prepared yellow OLEDs show high external quantum efficiency (EQE) of 11.6% and broad FWHM of 105 nm. The two‐color‐based white OLED is prepared with peak EQE of 9.2%, the 1931 CIE coordinate of (0.29, 0.31), and color rendering index of 79, proving that these new ionic iridium(III) complexes show a great potential for white electroluminescence.

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.

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.

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.

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.

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.

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.