Seed-Crystal-Assisted Space-Confined Growth of FASnI<sub>3</sub> Quasi-Single-Crystal Thick Films and Their Photodetection Characteristics
Weiyin Gao, Xin Liu, Hangfan Jin, Wangyue Li, Xiaobo Wang, Rui Huang, Gang Xing, He Dong, Yipeng Zhou, Zhongbin Wu, Chenxin Ran
Abstract
Sn-based perovskites are ideal eco-friendly candidates as an alternative to Pb-based ones in next-generation optoelectronics. However, a polycrystalline Sn-based perovskite thin film deposited from the spin-coating process suffers from high defect density and poor chemical stability, causing inferior performance of optoelectronic devices. Herein, we report the fabrication of a compact FASnI 3 quasi-single-crystal (QSC) thick film by developing a seed-crystal-assisted space-confined (SSG) strategy. The crystal growth dynamics in the SSG process is identified to be crystal size-dependent Ostwald ripening, and the key parameters are carefully investigated. After optimization, a compact n -type FASnI 3 QSC thick film can be produced with exceptional properties, including thickness of 12 μm, crystal size of 36.63 ± 12.24 μm, defect density of 5.68 × 10 12 cm –3, and charge mobility of 10.1 cm 2 V –1 s –1 . The corresponding photodetector exhibits self-driven detection ability and detectivity of 10 10 Jones at low bias of 0.1 V. This work opens up a new avenue for developing high-performing Sn-based optoelectronic devices.