Stable Red-Emission Mixed Halide CsPb(Br/I)₃ Perovskite Quantum Dots for LEDs

Red-emission mixed-halide CsPb(Br/I)₃ perovskite quantum dots (PeQDs) have demonstrated significant potential for light-emitting diodes (LEDs) owing to their excellent optical tunability and high color purity. However, surface defects and environmental sensitivity induce nonradiative recombination, resulting in low photoluminescence quantum yield (PLQY) and poor stability, thereby limiting their practical applications. Here, bromotrimethylsilane (TMSBr) was employed as a passivator for post-treatment to address these issues. TMSBr significantly enhances the PLQY from 26.6% to 98.1% by suppressing nonradiative recombination. The hydrophobic and bulky TMS group improves the environmental stability of PeQDs, enabling better resistance to air, ultraviolet radiation, and thermal stress. Density functional theory calculations further revealed that Br^- ions effectively passivate iodide vacancies, while the TMS group bonds with undercoordinated I^- ions, thereby enhancing surface stability. Based on these improvements, the fabricated white LEDs exhibit outstanding performance, achieving a high color rendering index of 91.6 and a significantly improved luminous efficacy of 70.6 lm/W. This study proposes a simple and efficient surface passivation strategy, offering new insights into the development of high-performance and stable CsPb(Br/I)₃ PeQD-based devices.