Violet Perovskite Quantum Dots of MA 3 Bi 2 Br 9 and MA 3 Bi 2 Br 6 Cl 3 Synthesized by the Cb‐LARP Method with Tunable Emission Wavelengths in Range of 379–400 nm

Violet‐emitting perovskite quantum dots (QDs) are of great significance for theoretical and experimental research aimed at promoting the development of environmentally friendly violet light‐emitting diodes (LEDs). Nevertheless, the synthesis of violet perovskite QDs via ligand‐assisted reprecipitation is challenging due to the significant bandgap. A simple and economical cryo‐bonding ligand‐assisted reprecipitation (Cb‐LARP) method is proposed as a means of synthesizing deep violet lead‐free organic‐inorganic hybrid perovskite (OIHP) QDs, with the objective of increasing the bandgap in the material. The MA 3 Bi 2 Br 9 QDs synthesized by the Cb‐LARP method exhibit bright violet luminescence at 400 nm, with a PLQY of 50.1%. Moreover, the photoluminescence peak of the QDs can be adjusted from 402 to 393 nm by modifying the final reaction time. It is noteworthy that the MA 3 Bi 2 Br 6 Cl 3 QDs exhibited ultraviolet emission at 379 nm, corresponding to a PLQY of 35.4%. Similarly, the emission peak of the QDs can be tuned from 379 to 376 nm by changing the final reaction time. The results demonstrate that the deep violet emitting OIHP QDs have been successfully synthesized. This study provides a theoretical reference for short‐wavelength perovskite materials and an experimental reference for the study of violet and UV quantum‐dot light‐emitting diode devices.