Highly Stable Perovskite Nanocrystals with Pure Red Emission for Displays

Inorganic metal halide perovskites have very promising applications in light-emitting diodes (LED), solar cells, lasers, and photodetectors owing to their outstanding optoelectronic characteristics. However, halide segregation is quite a challenge in the industrialization process of pure red perovskite LEDs with stable emission. In this work, we addressed this issue by doping with KBr in the nucleation of nanocrystals (NCs) and postmodifying with quaternary ammoniums (e.g., tetrabutylammonium bromide, TBAB). Mixed halide perovskite NCs (CsPbI3–xBrx NCs) with excellent optical performances and stabilities were obtained. The emission maximum was at ∼636 nm, and the full-width-at-half-maximum (fwhm) was 28 nm, achieving the requirement of Rec. 2020. The solution and film of KBr/TBAB-CsPbI3–xBrx NCs could keep pure red emission after exposure in the air for 65 and 90 days, respectively. The photoluminescence quantum yield (PLQY) of the KBr/TBAB-CsPbI3–xBrx NCs solution remained 90% and the emission peak had only a very slight shift after 240 h of irradiation at 365 nm. This study demonstrated an efficient route for highly stable pure red perovskite NCs and highlighted the critical role of surface ligands, which is expected to be applied in the future.