Investigation on optical properties of lead-free Cs₃Bi₂Br₉ perovskite derivative quantum dots synthesised via modified LARP method

Lead-free bismuth-based perovskite halides are promising materials for optoelectronic applications owing to their lower toxicity, high absorption coefficient, and similar isoelectronic structure to (lead) Pb. Herein, we report the synthesis of Cs₃Bi₂Br₉ perovskite quantum dots (QD) via a modified LARP method and have studied the structural and optical properties. In this study, the QD exhibits an interesting dual emission peak and a bright, unique cyan-green luminescence, with an improved photoluminescence quantum yield of 34%. Studies on Cs₃Bi₂Br₉ QD have been reported earlier, but interestingly the origin of optical properties remains disputed and varies significantly from literature to literature. As a result of our analysis, we expect observed photoluminescence to arise from interconfigurational electronic transitions of Bi³⁺ ions, with an intense peak at 476 nm attributed to A-band emission and a broad emission at 498 nm attributed to emission from a lower energy level in bismuth ion. Hence, these QDs are suitable for various optoelectronic applications, such as light-emitting diodes (LEDs).