Effect of Methylammonium Iodide (MACl) on MAPbI 3 -Based Perovskite UV-C Photodetectors.

In this study, we fabricated deep ultraviolet (DUV) photodetectors based on perovskite thin films doped with halide materials using formamidinium bromide (FABr) and methylammonium iodide (MAI). The device was fabricated using a simple surface engineering technique by post-treating the MAPbI₃ perovskite film with an FABr solution. This film acts as a light absorption layer, like a depletion layer with a p-i-n (PIN) structure, with n-type of SnO₂-SDBS and p-type of spiro-OMeTAD. Adding 0.10 M MACl to the MAPbI3 precursor solution during the manufacturing process could effectively reduce the trap density compared with existing films. Films with MACl added in the two-step process can control a wide band gap and improve crystallinity. In addition, the Cl atom has a smaller atomic radius than iodine and a higher electronegativity of 3.16, which can improve phase stability, and the effect of the added Cl⁻ increases the electron mobility of the perovskite, showing a fast response. [ABSTRACT FROM AUTHOR]