Giant Electric Bias‐Induced Tunability of Photoluminescence and Photoresistance in Hybrid Perovskite Films on Ferroelectric Substrates

Abstract Hybrid organic–inorganic perovskites represent the frontier of optoelectronic research due to their outstanding physical properties and remarkable photovoltaic performance. Despite the success of perovskite‐based photovoltaic devices, the investigation on tuning photoelectric properties of perovskites is still scarce. Here, giant modulations of photoluminescence (up to 91.3%) and photoresistance (up to 70.8%) are achieved in CH₃NH₃PbI₃ films by applying an electric bias on single‐crystal ferroelectric Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃ substrates. The results indicate that the electrostatic (converse piezoelectric) effect is predominant in thinner (thicker) film, resulting in rich optical and electronic tuning phenomena. This work integrates hybrid perovskites with piezoelectric platforms, paving the way toward solution‐processed piezophototronic and bias‐tunable optoelectronics.