Strain engineering and epitaxial stabilization of halide perovskites

• Published in: Nature (London) Vol. 577; no. 7789; pp. 209 - 215
• Main Authors: Chen, Yimu, Lei, Yusheng, Li, Yuheng, Yu, Yugang, Cai, Jinze, Chiu, Ming-Hui, Rao, Rahul, Gu, Yue, Wang, Chunfeng, Choi, Woojin, Hu, Hongjie, Wang, Chonghe, Li, Yang, Song, Jiawei, Zhang, Jingxin, Qi, Baiyan, Lin, Muyang, Zhang, Zhuorui, Islam, Ahmad E., Maruyama, Benji, Dayeh, Shadi, Li, Lain-Jong, Yang, Kesong, Lo, Yu-Hwa, Xu, Sheng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09.01.2020; Nature Publishing Group
• Subjects: 140/133; 140/146; 142/126; 639/301/299/946; 639/301/357/995; Compressive properties; Control; Crystal lattices; Crystal structure; Electric properties; Engineering; Epitaxial growth; Epitaxy; Halides; Hole mobility; Humanities and Social Sciences; Industrial engineering; Influence; Iodides; Iodine; Materials; Methods; multidisciplinary; Neutralization; Optical properties; Optoelectronic devices; Organic chemistry; Perovskite; Perovskites; Phase transitions; Science; Science (multidisciplinary); Semiconductor films; Single crystals; Spectrum analysis; Stabilization; Strain analysis; Strains and stresses; Stress relaxation (Materials); Stress relieving (Materials); Substrates; Synergistic effect; Thermal expansion; Thin films; United States
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-019-1868-x

Strain engineering is a powerful tool with which to enhance semiconductor device performance 1 , 2 . Halide perovskites have shown great promise in device applications owing to their remarkable electronic and optoelectronic properties 3 – 5 . Although applying strain to halide perovskites has been frequently attempted, including using hydrostatic pressurization 6 – 8 , electrostriction 9 , annealing 10 – 12 , van der Waals force 13 , thermal expansion mismatch 14 , and heat-induced substrate phase transition 15 , the controllable and device-compatible strain engineering of halide perovskites by chemical epitaxy remains a challenge, owing to the absence of suitable lattice-mismatched epitaxial substrates. Here we report the strained epitaxial growth of halide perovskite single-crystal thin films on lattice-mismatched halide perovskite substrates. We investigated strain engineering of α-formamidinium lead iodide (α-FAPbI 3 ) using both experimental techniques and theoretical calculations. By tailoring the substrate composition—and therefore its lattice parameter—a compressive strain as high as 2.4 per cent is applied to the epitaxial α-FAPbI 3 thin film. We demonstrate that this strain effectively changes the crystal structure, reduces the bandgap and increases the hole mobility of α-FAPbI 3 . Strained epitaxy is also shown to have a substantial stabilization effect on the α-FAPbI 3 phase owing to the synergistic effects of epitaxial stabilization and strain neutralization. As an example, strain engineering is applied to enhance the performance of an α-FAPbI 3 -based photodetector. A method of deposition of mixed-cation hybrid perovskite films as lattice-mismatched substrates for an α-FAPbI 3 film is described, giving strains of up to 2.4 per cent while also stabilizing the metastable α-FAPbI 3 phase for several hundred days.