A formamidinium–methylammonium lead iodide perovskite single crystal exhibiting exceptional optoelectronic properties and long-term stability

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 5; no. 36; pp. 19431 - 19438
• Main Authors: Li, Wen-Guang, Rao, Hua-Shang, Chen, Bai-Xue, Wang, Xu-Dong, Kuang, Dai-Bin
• Format: Journal Article
• Language: English
• Published: 2017
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C7TA04608A

Halide perovskite single crystal of cubic HC(NH 2 ) 2 PbI 3 (FAPbI 3 ) having excellent optoelectronic properties, such as narrow bandgap, large absorption coefficient and superior thermal stability has caught a surge of attention as a promising material for production of high-performance optoelectronic devices. However, at room temperature, the self-transformation of cubic FAPbI 3 perovskite phase to non-perovskite phase leaves a critical roadblock to its practical viability. Herein, a simple alloying strategy by mixing methylammonium with formamidinium is developed to stabilize the FAPbI 3 perovskite phase, hence achieving a highly stable mixed cation MA 0.45 FA 0.55 PbI 3 perovskite single crystal over a span of 14 months. The MA 0.45 FA 0.55 PbI 3 single crystal exhibits exceptional optoelectronic properties like high carrier mobility of 271 ± 60 cm 2 s −1 V −1 and long diffusion length up to 254 μm, which are twice the values for sole MAPbI 3 or FAPbI 3 crystals. In addition, the photodetector based on MA 0.45 FA 0.55 PbI 3 single crystal exhibits low detection limit of about 1 nW cm −2 , high ON–OFF ratio of ∼1000, short response time of less than 200 μs, and impressive stability under aging in dark for 4 months or continuous photo-switching test for 1000 s.