To improve the quantum efficiency and stability of perovskite quantum dots, the structural and optical properties are optimized by varying the concentration of Ni doping in CsPbBr3 perovskite nanocrystals (PNCs). As Ni doping is gradually added, a blue shift is observed at the photoluminescence (PL) spectra. Ni‐doped PNCs exhibit stronger light emission, higher quantum efficiency, and longer lifetimes than undoped PNCs. The doped divalent element acts as a defect in the perovskite structure, reducing the recombination rate of electrons and holes. A stability test is used to assess the susceptibility of the perovskite to light and moisture. For ultra‐violet light irradiation, the PL intensity of undoped PNCs decreases by 70%, whereas that of Ni‐doped PNCs decreases by 18%. In the water addition experiment, the PL intensity of Ni‐doped PNCs is three times that of undoped PNCs. For CsPbBr3 and Ni:CsPbBr3 PNCs, a light emitting diode is fabricated by spin‐coating. The efficiency of Ni:CsPbBr3 exceeds that of CsPbBr3 PNCs, and the results significantly differ based on the ratio. A maximum luminance of 833 cd m–2 is obtained at optimum efficiency (0.3 cd A–1). Therefore, Ni‐doped PNCs are expected to contribute to future performance improvements in display devices.

Three V-shaped host molecules with a cyclohexane linker were successfully synthesized for thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The unipolar host molecules, BBCzC and BTDC, contained two 9-phenyl-9H-3,9′-bicarbazole (PBCz) moieties and two 2,12-di-tert-butyl-7-phenyl-5,9-dioxa-13b-boranaphtho­[3,2,1-de]­anthracene (PDBNA) moieties, respectively. BCzTC, a bipolar host molecule, consisted of a donor unit, PBCz, and an acceptor unit, PDBNA, connected by a cyclohexane linker. Three host molecules showed good solubility in various organic solvents, making them suitable for solution processing. Among the solution-processed green TADF-OLEDs using three host molecules and a green TADF emitter, the one with BCzTC showed the highest external quantum efficiency of up to 30% with a high power efficiency of 71 lm W–1 and a current efficiency of 102 cd A–1. Compared with BBCzC and BTDC, BCzTC exhibited a relatively high photoluminescence quantum yield (PLQY), an excellent balance in hole and electron transport properties in the emitting layer, and more efficient energy transfer to the emitter, giving such an excellent device performance.

Development of suitable host materials for application to an emitter is of significant importance for the high-efficiency organic light-emitting diodes (OLEDs). In this study, we successfully synthesized poly(9,9-diphenyl-10-(4-vinylbenzyl)-9,10-dihydroacridine) (P(Bn-DPAc)) as...

An entropic coefficient of reversible entropic heat is a key parameter in determining the battery thermal responses, but its measurement is challenging due to time consuming and inaccurate traditional methods. In this regard, an analytical approach based on the inverse heat transfer problem is newly proposed to precisely determine the entropic coefficient with low experiment cost. Experiments are conducted by discharging the battery under four different current rates to inversely estimate the entropic coefficients, and the least squares regression are conducted to optimize the derived entropic coefficients. Through the comparison with the existing potentiometric method, the experimental time can be reduced by 93.7%. Furthermore, the accuracy of the proposed method is well verified by validating within the root mean square error of 0.848°C by comparing with the experimental results. Through the validation processes under various operating conditions, such as low to high current rates, charging process, dynamic loads, and different ambient temperatures, the proposed method is proven over temperatures ranging from 10°C to 60°C. Conclusively, the proposed method can be a great alternative to replace the classical experimental methods.