Distinct Strain‐Driven Photoresponse Mechanisms in Self‐Powered p‐ and n‐Type Halide Perovskite Photodetectors
Da Bin Kim, Kwan Sik Park, Kyeong Su Jo, Seok Mo Yang, Yong Soo ChoABSTRACT
Strain engineering has emerged as a promising approach for tuning the optoelectronic properties of halide perovskites. Certain halides exhibit enhanced performance under compressive strain, whereas others respond more favorably to tensile strain, governed by mechanisms including lattice distortion, trap‐state modulation, strain‐induced band alignment, and piezo‐phototronic coupling. Herein, weakly p‐type MAPbI 3 (methylammonium lead iodide) and strongly n‐type CsPbBr 3 are employed as representative halide perovskites to directly compare their strain‐dependent self‐powered photoresponses under externally applied tensile and compressive strains ranging from +0.68% to −0.68%. Under the maximum compressive strain of −0.68%, the MAPbI 3 and CsPbBr 3 photodetectors exhibit peak photoresponsivities of 695 and 255 mA W −1 , respectively, together with broadened 3 dB bandwidths of 219 and 313 kHz. Despite similar performance enhancements, MAPbI 3 is dominated by lattice‐strain‐induced trap suppression, whereas CsPbBr 3 primarily benefits from strain‐improved band alignment and hole transport. In both systems, piezo‐phototronic modulation further promotes charge separation and extraction. This work establishes a unified framework for distinguishing the respective roles of lattice strain and piezo‐phototronic effects in self‐powered halide perovskite photodetectors.