Scalable synthesis of highly luminescent and stable thiocyanate based CsPbX3 perovskite nanocrystals for efficient white light-emitting diodes

Abstract All-inorganic lead halide perovskites have attracted considerable attention as promising materials for optoelectronic devices because of their excellent photophysical properties. However, the stability issue of halide perovskites precludes their practical applications. For the first time, this work exhibits that the optical properties and stability of CsPbX3 perovskite nanocrystals (NCs), prepared by the saponification precipitation method, can be improved using thiocyanate (SCN−). Besides, this work offers a simple and economical synthesis method operable at room temperature and ambient atmosphere. Specifically, an increasing concentration of SCN− induces an increase in quantum yield almost by 10% and stability against air and moisture over several days due to the better passivation of trap states, irrespective of size and shape variation of NCs. The demonstration of tunable emission (454–645 nm) across the visible spectrum and the design of 3-D printed thin layers facilitate the preparation of green, yellow, and red-emitting color conversion layers. Benefitted from the decreased photon loss in as-synthesized conversion layers, the application of these color conversion layers results in a bright neutral white light (5184 K) with remarkable optical properties. Hence, this experimental study offers a low-temperature synthetic path for the scalable preparation of high-quality CsPbX3 NCs processed with SCN− and reveals the practical applications of such NCs.