Near‐Unity Quantum Yield and Superior Stable Indium‐Doped CsPbBrxI3−x Perovskite Quantum Dots for Pure Red Light‐Emitting Diodes

Although all-inorganic CsPbBrxI3-x perovskite quantum dots (PeQDs) are increasingly being used as a competitive material for pure red perovskite light-emitting diodes (PeLEDs), they suffer from low luminescent ability and poor stability. In this study, an In3+-doped CsPbBrxI3-x PeQD solution exhibits a near-unity photoluminescence quantum yield (PLQY) of approximate to 99.8% and superior stability for more than half a year in atmosphere. As far as known, this is the highest PLQY and stability achieved for mixed halide PeQDs. In3+ ion doping not only reduces the surface vacancy defects because of the partial substitution of Pb2+ by the smaller radii of In3+ ions, but also enhances the formation energy of CsPbBrxI3-x PeQDs based on first-principles calculations. Compared with pristine LEDs based on CsPbBrxI3-x, the pure red PeLEDs based on In3+-doped CsPbBrxI3-x display a higher luminance of 423 cd m(-2), fivefold external quantum efficiency improvement up to 11.2%, and increased stability, providing a feasible and promising perspective for developing In3+-doped CsPbBrxI3-x PeQDs applied efficiently in advanced light emitters for solid-state lighting and displays.