Strain engineering and epitaxial stabilization of halide perovskites

Abstract

Strain engineering is a powerful tool with which to enhance semiconductor device performance . Halide perovskites have shown great promise in device applications owing to their remarkable electronic and optoelectronic properties . Although applying strain to halide perovskites has been frequently attempted, including using hydrostatic pressurization , electrostriction , annealing , van der Waals force , thermal expansion mismatch , and heat-induced substrate phase transition , 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 ) 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 thin film. We demonstrate that this strain effectively changes the crystal structure, reduces the bandgap and increases the hole mobility of α-FAPbI . Strained epitaxy is also shown to have a substantial stabilization effect on the α-FAPbI 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 -based photodetector. 1,2 3–5 6–8 9 10–12 13 14 15 3 3 3 3 3