Direct Growth of Pyramid‐Textured Perovskite Single Crystals: A New Strategy for Enhanced Optoelectronic Performance

Abstract Even though there have been a few reports of substrate surface texturing of thin film perovskite solar cells to enhance their light trapping, there has been no direct texturing of the perovskite material, let alone perovskite single crystals (SCs). Herein, a method to prepare a pyramid‐structured perovskite CH 3 NH 3 PbX 3 (CH 3 NH 3 + = MA, X = I, Br) SC surface with minimized light reflection and maximized incident light harvesting is reported. Specifically, a hard template is used to directly transfer the pyramidal texture onto the MAPbX 3 SC during its growth. A well‐shaped pyramidal texture is formed on the single‐crystal surface leading to improved light trapping. The textured MAPbBr 3 SC shows good crystallinity, prolonged carrier lifetime, and improved carrier mobility. Furthermore, the photodetector made from the textured SC shows enhanced responsivity of 321 A W −1 and external quantum efficiency of 7191%, about two times higher than that of a control device. This method may be used to directly fabricate desired textures on general single crystal surfaces.