The rapid development of halide perovskite synthesis offers the opportunity to fabricate high-quality perovskite nanocrystals (NCs), whose structural uniformity can lead to assembled supra-structures with improved device performance and novel collective properties. Light is known to significantly affect the structure and properties of halide perovskites and plays a crucial role in the growth and assembly of their crystals. Nevertheless, the light-induced growth mechanisms of perovskite NCs are not yet clearly understood. In this work, we performed a systematic study of the visible-light-induced template-free synthesis of CsPbBr3 nanowires (NWs) generated through self-assembly of cubic (in phase and close to cubic morphology) NCs. Using atomic-resolution electron microscopy, we visualized the cubic-to-orthorhombic phase transition in NCs and the interface between coalesced NCs. Remarkably, the images of the interface revealed the coexistence of CsBr and PbBr2 surface terminations in halide perovskites. Our results shed light on the mechanism underlying the observed anisotropic assembly of halide perovskites and elucidate the vital role of light illumination during this process. More importantly, as an elegant and promising green-chemistry approach, light-induced self-assembly represents a rational method for designing perovskites.
KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by King Abdullah University of Science and Technology (KAUST). Xin Liu was supported by the National Science Foundation of China (NSFC, No.: 21771029 and 21573034). J. Liu would like to acknowledge Dr. Jiangtao Jia from KAUST Advanced Membranes and Porous Materials Center for his valuable suggestions. The supercomputer time was supported by the Supercomputing Core Laboratory at KAUST.