Thickness-dependent carrier lifetime and mobility for MAPbBr₃ single

Carrier transfer is a key process for perovskite-based photoelectric conversion. It has a close relationship with grain boundaries, grain size, and contact layers. Understanding this relationship is of great significance for revealing the inherent characteristics of perovskite materials and for devices optimization. However, the dependence of carrier transfer characteristics (including carrier lifetime and mobility) on thickness is less studied, although which is a key issue for almost all perovskite material devices. Here we find that as the thickness of MAPbBr(3) perovskite single crystal (PSC) increases from 1.47 mm to 10.55 mu m, the carrier lifetime of MAPbBr(3) decreases from 70 ns to 30 ns, and the carrier mobility decreases from 97 cm(2) V-1 s(-1) to 57 cm(2) V-1 s(-1), but they become constant in very thick samples. In addition, it was found that as the crystal thickness increased from 1.47 mu m to 10.55 mu m, the surface layer range gradually increased from 12 nm to 31 nm. The surface recombination velocity and surface defect (trap) density further confirmed that the thin PSC exhibited a small surface layer range. Finally, a three-layer carrier transmission model of PSC is proposed. This research provides guidance for the optimal design of PSC optoelectronic devices. (C) 2020 Elsevier Ltd. All rights reserved.