Aspect-ratio controllable growth of rectangular cesium lead bromide crystallites on PTAA modified substrates

Micro–nano cesium lead halide perovskites have become one of the most potential materials for optoelectronic applications due to their excellent photoelectric properties such as tunable band gap, high absorption efficiency, long carrier diffusion length, and high stability. Although significant efforts have been made to grow CsPbBr3 single crystal perovskites via solution processing, it is difficult to prepare discrete high-quality factors and small volumes of Fabry–Pérot (F–P) mode and whispering-gallery-mode (WGM) optical resonators on the substrate due to random nucleation and excessive nucleation points, which lead to the accretion of a large number of crystallites. In this work, CsPbBr3 crystallites with different aspect ratios have been prepared on poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) modified glass substrates by combining the control of evaporation rate of anti-solvents with the coffee ring effect and Marangoni effect. Due to the hydrophobic properties of PTAA, the nucleation points are significantly reduced, resulting in the growth of high-quality and robust single crystals separated from each other. These crystallites exhibit a high-quality factor (Q = 1200–1600) with a threshold of 10–20 μJ cm−2. The results indicate that the prepared CsPbBr3 crystallites can be used as promising micro–nano F–P and WGM lasers.