Controlled synthesis and photostability of blue emitting Cs3Bi2Br9 perovskite nanocrystals by employing weak polar solvents at room temperature

Metal halide nanocrystals (NCs) have attracted intensive interest due to their unique optical properties and cheap synthesis which endows them with tremendous potential for application in the field of optoelectronic devices. However, lead toxicity obstructs their commercialization. Therefore, environment- and consumer-friendly all-inorganic lead-free perovskite NCs are highly desirable in terms of application, and recent efforts have investigated lead-free halide perovskite NCs. Herein, in this present work, all-inorganic Cs3Bi2Br9 perovskite NCs were synthesized for the first time with a weak-polar solvent at room temperature (WPRT). As-synthesized Cs3Bi2Br9 perovskite NCs demonstrated blue dual-emission peaks at 414 nm and 433 nm with a full width at half-maximum (FWHM) of 50 nm and a photoluminescence quantum yield (PLQY) up to 29.6%. Notably, the NCs exhibited high stability upon air exposure exceeding three weeks since the trap states could be passivated under humid conditions. Furthermore, it was also found that potassium oleate (K-OA) solution could enhance the PLQY of Cs3Bi2Br9 perovskite NCs.