Anisotropic In Situ Strain‐Engineered Halide Perovskites for High Mechanical Flexibility. (14th October 2020)

• Record Type: Journal Article
• Authors: Kim, Da Bin; Lee, Jung Won; Cho, Yong Soo
• Is Part Of: Advanced functional materials. Volume 31:Number 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-14
• Subjects: flexibility -- fracture toughness -- halide perovskites -- strain engineering; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202007131
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Even though halide perovskite materials have been increasingly investigated as flexible devices, mechanical properties under flexible environments have rarely been reported on. Herein, a nonconventional deposition technique that can generate extra compressive or tensile stress in representative inorganic CsPbBr3 and hybrid MAPbI3 (methylammonium lead iodide) halide perovskites is proposed for higher mechanical flexibility. As an impressive result of bending fracture evaluation, fracture energy is substantially improved by ≈260% for CsPbBr3 and ≈161% for MAPbI3 with the maximum compressive strain of −1.33%. Origin of the flexibility enhancements by the in situ strain is verified with structural simulation where the anisotropic lattice distortion, that is, contraction in the ab plane and elongation along the c ‐axis, is evident with changes in atomic bond lengths and angles in the halide perovskites. Other mechanical properties such as hardness, film strength, and fracture toughness are also discussed with direct comparisons between the inorganic and hybrid halides. Beyond the successful adjustment of this in situ deposition technique, the strain‐dependent mechanical properties are expected to be extensively useful for designing halides‐based flexible devices. Abstract : An in situ strain deposition process is applied to perovskite halide thin films for higher mechanical flexibility. Significantly improved fracture resistance is evident with intentional compressive stress, which is enabled by the contraction of PbX bond length and the distortion of PbX6 octahedra. This in situ strain process is extendable to a variety of other flexible devices seeking desirable strain‐modulations.