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Although sensitizing traditional fluorescent dyes with thermally activated delayed fluorescence (TADF) exciplexes has been extensively studied, the device performance of solution‐processed organic light‐emitting diodes (OLEDs) still lags far behind in this regard. Herein, the novel exciplex with high up‐conversion efficiency composed of a triazatruxene‐based donor and a triazine‐based acceptor is employed as a TADF sensitizer to fluorescent dye in solution‐processed hyperfluorescent OLEDs. Benefiting from the small activation energy for triplet up‐conversion and less non‐radiative recombination of triplet excitons, the new TADF exciplex can up‐convert efficiently non‐radiative triplet excitons through reverse intersystem crossing. Besides, expeditious up‐conversion processes also shorten the residence time of triplet excitons, giving rise to significant suppression of detrimental Dexter energy transfer from the exciplex sensitizer to the dopant. By maximizing the triplet up‐conversion efficiency of exciplex sensitizers, the optimized OLEDs achieve a maximum external quantum efficiency (EQEmax) of 16.0%, which is the first report for the solution‐processed exciplex‐sensitized hyperfluorescent OLEDs with EQEmax exceeding 15%. These results validate that the up‐conversion efficiency of triplet excitons in the exciplexes strongly affects the performance of exciplex‐sensitized fluorescent devices, and the triazatruxene‐based molecules are promising donor candidates for constructing the exciplexes with high up‐conversion efficiency. [ABSTRACT FROM AUTHOR]

Excessive organic ligands damage the crystallinity of blue quasi‐2D perovskite, resulting in a small‐grain film with a high grain boundary ratio. Herein, oriented blue perovskite nanoplates are fabricated by using antisolvent additive engineering to tackle this issue. The introduction of triphenylphosphine oxide additive in antisolvents significantly increases the perovskite grain sizes, laying the foundation for in situ formation of perovskite nanoplates. The miscibility between ethyl acetate antisolvent and dimethyl sulfoxide host solvent affects formation of the oriented perovskite nanoplates. The perovskite film containing oriented nanoplates with enhanced crystallinity exhibits elevated photoluminescence quantum yield as compared to the control samples. Based on the oriented perovskite nanoplates, blue perovskite light‐emitting diodes (PeLEDs) with an emission peak at 488 nm and a maximum external quantum efficiency of 9.5% are successfully fabricated. Moreover, the blue PeLEDs deliver a high brightness of 4256 cd m–2 with stable electroluminescent spectra. [ABSTRACT FROM AUTHOR]

Inorganic metal halide perovskite quantum dots (QDs) have emerged as a new class of solution-processable semiconductor materials for next-generation displays. However, such QDs commonly suffer from surface defects, resulting in low photoluminescence quantum yields (PLQYs) and inefficient charge carrier transport in perovskite QD based light-emitting diodes (perovskite QD-based LEDs). Herein, we propose an effective strategy of introducing gallium (Ga) cations to passivate surface defects in the CsPbBr3 QDs for the fabrication of bright perovskite QD-based LEDs. Partial Ga cations in the CsPbBr3 QD surfaces are beneficial for their surface defect passivation and their crystalline quality. Correspondingly, the radiative recombination and carrier mobility are greatly enhanced compared with the pristine ones. The PLQY of CsPbBr3 QDs passivated with 40% Ga cations is increased from 60.2% to 86.7%. The corresponding perovskite QD-based LEDs exhibit a maximum brightness of 11 777 cd m−2, more than two times higher than that of the pristine QD-derived device. The corresponding operational stability is also greatly enhanced relative to the pristine-derived device. The proposed Ga cation passivation strategy paves the way toward the fabrication of highly efficient perovskite QD-based LEDs for applications such as perovskite QD-based LED displays and light conversion based micro-LED displays. [ABSTRACT FROM AUTHOR]

Gaseous CO2 reduction driven by solar energy is a promising solution to the current energy crisis and environmental problems. Although thermocatalysts, electrocatalysts, and photocatalysts are developed as classical strategies for CO2 reduction, it remains a challenge for high efficiency and CO2 net reduction during this process. Here, a multi‐field driven hybrid catalyst, Pt/ZnO nanorod arrays/Bi1‐xErxCuSeO, is designed using the photo‐thermoelectric effect, which can take advantage of both photocatalysis and thermocatalysis. The results indicate that the maximum CO production rate of 2.91 µmol g−1 h−1 at 423 K can be realized in such Pt/ZnONR/Bi0.9Er0.1CuSeO hybrid catalyst, as can be ascribed to a synergetic photo‐thermoelectric effect (i.e., light irradiation can provide heat, photo‐excited carriers, and the concomitant Seebeck voltage). The band alignment of ZnO/BiCuSeO heterojunction and carriers transport are proposed to be optimized by the Er doped BiCuSeO thermoelectric supports, greatly enhancing the catalytic performance. The application of thermoelectric support could be promising in the structure design of multi‐field driven hybrid catalysts, and such a photo‐thermoelectric catalytic process demonstrates a desirable way of solar energy utilization in CO2 transformation. [ABSTRACT FROM AUTHOR]

Gallium (Ga) doping together with low dimensionality has been a promising approach to improve thermoelectric performance of zinc oxide (ZnO) materials, due to the increase of carrier concentration and suppression of phonon transport. So far, the highest power factor of Ga‐doped ZnO (GZO) thin films has reached 280 μW m−1 K−2, which is still limited for practical applications. In this work, we have simultaneously optimized the electrical conductivity and Seebeck coefficient of GZO thin films using the combination of oxygen defects and sandwich structure (GZO‐ZnO‐GZO). Benefiting from energy filtering effect at the interface between GZO and ZnO layers and high oxygen vacancy concentration, the density of states (DOS) effective mass has been increased together with a relatively high carrier concentration. As a result, an improved power factor value of 434 μW m−1 K−2 at 623 K has been achieved, which is comparable to the best values reported for ZnO‐based films. This method of combining defect engineering and sandwich structure design shows great potential in enhancing the thermoelectric performance of ZnO‐based thin films or other oxide materials. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS), a promising non-precious electrocatalyst for the hydrogen evolution reaction with two-dimensional layered structure, has received increasing attention in recent years. Its electrocatalytic performance has been limited by the low active site content and poor conductivity. Herein, we report a facile and general ultrafast laser ablation method to synthesize MoS quantum dots (MS-QDs) for electrocatalytic HER with fully exposed active sites and highly enhanced conductivity. The MS-QDs were prepared by ultrafast laser ablation of the corresponding bulk material in aqueous solution, during which they were partially oxidized and formed defective structures. The as-prepared MS-QDs demonstrated high activity and stability in the electrocatalytic HER, owing to their very large surface area, defective structure, abundance of active sites, and high conductivity. The present MS-QDs can also find application in optics, sensing, energy storage, and conversion technologies. [ABSTRACT FROM AUTHOR]

An osmotically swollen ammoniated MoS2 electrocatalyst for hydrogen evolution is developed via a simple hydrothermal route for the first time. The applied relatively high temperature and pressure promote the diffusion of NH4+ ions into MoS2 lamellar structures, leading to the formation of ammoniated MoS2 with remarkable lattice expansion. The insertion of NH4+ ions induces a great enhancement in the electrical conductivity of MoS2, resulting in an excellent activity for the hydrogen evolution reaction with a small Tafel slope of 45 mV dec−1, which is amongst the best recorded for MoS2-based catalysts, making it a very promising electrocatalyst to replace Pt-based ones. [ABSTRACT FROM AUTHOR]

Perovskite oxide, a low‐cost bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalyst, has acquired a rapidly growing research interest in the areas of energy conversion and storage, owing to its significant surface structure‐induced catalytic performance. Here, recent progress on the electrocatalytic performance of La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) is built by engineering its surface defect structure through a versatile, effective, and controllable lithium reduction strategy. It is established that the lithium reduction treatment causes the formation of a structurally disordered layer at the surface of LSCF nanoparticles. The treated nanoparticles demonstrate significantly enhanced OER and ORR performance, especially for 5 wt% lithium‐reduced LSCF, whose OER potential decreases from 1.66 to 1.55 V at current density of 10 mA cm−2, and ORR onset potential increases from 0.70 to 0.84 V. This work provides the foundation for the optimization of catalytic performance of perovskite oxide (LSCF). Moreover, such defective materials are promising candidates for energy conversion and storage applications. The surface structure of perovskite oxides plays a crucial role on their electrocatalytic performance. Herein, La0.6Sr0.4Co0.2Fe0.8O3–δ nanopowders with defective surface structure are prepared a controllable, facile, and general lithium reduction method, showing significantly improved electrocatalytic oxygen evolution reaction and oxygen reduction reaction activity and stability owning to the enhanced oxygen exchange kinetics, electrical conductivity, and structural durability. [ABSTRACT FROM AUTHOR]

Because of the high carrier concentration, copper telluride (Cu 2 Te) has a relatively low Seebeck coefficient and high thermal conductivity, which are not good for its thermoelectric performance. To simultaneously optimize carrier concentration, lower thermal conductivity and improve the stability, BiCuTeO, an oxygen containing compound with lower carrier concentration, is in situ formed in Cu 2 Te by a method of combining self-propagating high-temperature synthesis (SHS) with spark plasma sintering (SPS). With the incorporation of BiCuTeO, the carrier concentration decreased from 8.1 × 10 20 to 3.8 × 10 20 cm -3 , bringing the increase of power factor from ~1.91 to ~2.97 μW cm -1 K -2 at normal temperature. At the same time, thermal conductivity reduced from 2.61 to 1.48 W m -1 K -1 at 623 K. Consequently, (Cu 2 Te) 0.95 -(BiCuTeO) 0.05 composite sample reached a relatively high ZT value of 0.13 at 723 K, which is 41% higher than that of Cu 2 Te.

In work, (002) oriented flower-like Bi 2 O 2 CO 3 (BOC) composites are synthesized by a facile chemical route and carbon quantum dots (CQDs) are modified on their surfaces through a hydrothermal method. The synthesized samples (CQD/BOC) are characterized by X-ray diffraction (XRD), SEM, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuser reflectances (DRS), BET and TEM/HRTEM. The morphologies of CQD/BOC composites are the flower-like shapes, the irregular flaky structures and the fine spherical particles of CQDs attached. Photocatalytic performances were investigated in terms of removing gaseous toluene at a concentration of 94.3ppm in air, with the assistance of CQD/BOC under artificial irradiation. Our results show that CQDs modified (002) oriented Bi 2 O 2 CO 3 exhibits good photocatalytic activity for toluene decomposition, which can be attributed to the enhanced efficient charge separation. A certain ratio composite photocatalyst (BOC-CQD-15) shows a toluene removal rate of 96.62% in three hours, as well as great stability. CO 2 was verified to be the primary product. The oriented flower-like Bi 2 O 2 CO 3 with carbon quantum dots on the surface shows great potential in the field of solar driven air purification.

Large-size ultrathin two-dimensional (2D) metals with a fully exposed (111) surface have been synthesized by a heat-pressing process. As a result of the compact (111) surface arrangement, an ultrathin Pt 5 nm 2D metal exhibits a superior methanol electro-oxidation performance than an as-sputtered Pt 5 nm thin film (1.8, 2.2 and 5.0 times higher specific activity under different scanning cycles).