Improving Stability of Cesium Lead Iodide PerovskiteNanocrystals 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.