Enhancing pure red perovskite LEDs via In-Situ etching and pseudohalide passivation of mixed halide quantum dots

Mixed-halide bromine-iodine perovskite quantum dots (PeQDs) exhibit remarkable spectral tunability, making them highly suitable for pure red perovskite light-emitting diodes (PeLEDs). However, surface defects in these PeQDs facilitate halide ion migration and non-radiative recombination, which impair PeLED performance. Here, we introduce an innovative post-treatment strategy employing pseudohalogen inorganic ligands in acetonitrile to simultaneously etch lead-rich surfaces and passivate defects in-situ . This method produces high-quality CsPb(Br/I) 3 PeQDs with suppressed halide migration, enhanced photoluminescence quantum yield (PLQY), and improved film conductivity. Consequently, our spectrally stable champion PeLEDs achieve a peak external quantum efficiency (EQE) of 22.1%, one of the highest reported for mixed-halide CsPb(Br/I) 3 PeQDs, representing a significant advancement in perovskite optoelectronics.