Air-stable cesium lead bromide perovskite nanocrystals via post-synthetic treatment with oleylammonium bromides

Abstract

Although past years have witnessed tremendous promises of cesium lead halide perovskite nanocrystals (CsPbX₃ NCs), realization of high performance devices based on CsPbX₃ NCs with sufficient reliability is still seriously hampered due to their instability. The representative consequence of instability in CsPbX₃ NCs is merging occurring under air conditions. When the CsPbX₃ NCs are exposed to air, their bright photoluminescence is rapidly diminished because charge carrier radiative recombination is hindered in enlarged domains. Because CsPbX₃ NCs merge along a specific direction (surface), merging-free CsPbX₃ NCs can be synthesized by controlling the surface chemistry. In this study, we developed an effective post-synthetic strategy to completely redesign the surface of CsPbX₃ NCs. The post-synthetically modified surfaces of CsPbX₃ NCs after treatment with oleylammonium halides exhibited significantly enhanced stability, whose morphology showed nearly no evidence of merging in air. Electron microscopy and quantitative spectroscopy studies revealed that controllable atomic layer etching, which results in the removal of the merging-vulnerable (110) surface, occurs on the surface of CsPbX₃ NCs by our post-synthetic treatment with oleylammonium halides. Finally, we proposed a mechanism derived from our effective post-synthetic chemistry, thus realizing high stability of CsPbX₃ NCs.