Nanopatterning on Mixed Halide Perovskites for Promoting Photocurrent Generation of Flexible Photodetector

Nanoimprinting lithography (NIL) technique is widely utilized for nanostructure engineering of soft materials. Owing to the soft organic/inorganic hybrid nature, the optical and crystallographic properties of halide perovskites (HPs) are improved by the NIL process. However, the wide application of NIL into various HPs has lagged. Herein, a defect-free nanopatterned-(FAPbI₃)_0.85(MAPbBr₃)_0.15 (NP-FAMA) film is successfully developed via optimized NIL. As surface energy is a key parameter to be controlled for accomplishing NIL process, trichloro(1H,1H,2H,2H-perfluorooctyl)silane (CF₃(CF₂)₅CH₂CH₂SiCl₃) treatment on polymeric mold, which prevents the peeling-off problem. Along with surface morphology modification, NP-FAMA exhibits enhanced crystallographic and photophysical properties. The photoresponsivity of NP-FAMA-based photodetectors outperforms bare (b-) FAMA-based devices. Surprisingly, the external quantum efficiency (EQE) of the NP-FAMA-based devices dramatically increases to 225%, photomultiplication (PM), under 1 nW illumination without any charge-injecting materials. To clarify these PM phenomena, the trap-assisted PM mechanism is suggested as a model system for promoting photocurrent generation of HPs that is supported by PL analysis.