Interface Engineering of Lead-Free Perovskite Quantum Dots for High-Performance Data Encryption and Ultralow UV-Light Detection

Abstract

Recently discovered lead-free perovskite quantum dots (QDs) have been touted as a new non-toxic star material that will replace lead-containing perovskite materials. However, its potential applications have not been advanced due to their high density of defect states. On the other hand, it is almost impossible to precisely control the luminescence of organic chromophores from different excited states with different emission colors. Here, we addressed these two great challenges in a single experiment by expanding the utility of lead-free perovskite materials capped with luminescence chromophores into brand new research directions and light-harvesting application. More specifically, we have successfully promoted the use of lead-free perovskite QDs as an efficient and reversible switch for chromophore luminescence for sensitive UV-light detection, with an extremely low detection limit of 74 picoW/cm2 and high-performance data encryption. Our time-resolved absorption and luminescence experiments, and density functional theory calculations have clearly demonstrated that ultrafast electron transfer from the optical excited Cs3MBi2Cl9 perovskite QDs tune and control the nature of neighboring organic chromophore luminescence, leading to different emission colors from different electronic excited states. This variation in interface color in response to different excitation energies provides a feasible strategy for high-performance information anti-counterfeiting and the ultralow detection limit of ultraviolet light.