Improving Stability of Cesium Lead Iodide Perovskite Nanocrystals by Solution Surface Treatments

Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wavelength range with a high quantum yield. They hold great potential for optoelectronic applications such as light-emitting diodes or electronic displays. However, cesium lead iodide (CsPbI₃) is not stable under ambient conditions, limiting its applications. Here, we use a solution surface treatment approach to improve the photostability of CsPbI₃ suspensions in toluene. When a CsPbBr₃ precursor is used via the method of heterogeneous surface treatment, the photoluminescence (PL) intensity is enhanced but the PL only lasts 2 days. In contrast, when a CsPbI₃ precursor is used via the method of homogeneous surface treatment, not only the PL intensity of CsPbI₃ suspensions is enhanced but also the stability with the PL lasts for 11 days. It is likely that a better protection on the core CsPbI₃ by itself can be achieved because of better matching of the material structure and surface chemistry.