Significantly Enhanced Emission Stability of CsPbBr₃ Nanocrystals via Chemically Induced Fusion Growth for Optoelectronic Devices

Maria Morrell, Xiaoqing He, Guangfu Luo, Arashdeep Thind, Tommi White, Jordan Hachtel, Albina Borisevich, Juan-Carlos Idrobo, Rohan Mishra, and Yangchuan Xing, ACS Applied Nano Materials 2018

Lead-halide perovskite nanocrystals (PNCs) have attracted much attention in recent years due to their outstanding optical properties. We report here a new chemical route for triggering post-synthetic growth of CsPbBr3 PNCs at room temperature via intentional depletion of stabilizing ligands, resulting in an immediate fusion growth of the as-synthesized PNCs. Upon fusion, the CsPbBr3 PNCs can grow from ca. 8 nm to ca. 60 nm in lateral dimensions in 48 hours, reaching about 14 nm in thickness. More importantly, it was found that the fused PNCs have significantly enhanced optical properties. They showed an exceptionally higher stability to photodegradation. They also displayed sharper emission lines and a higher quantum yield, contrary to the fact that the nanocrystals are much larger. The much-improved optical properties are attributed to the Ruddlesden-Popper planar faults formed during the fusion process and observed using atomic resolution scanning transmission electron microscopy, which are predicted to result in quantum confinement based on density-functional theory calculations.