Organic–Inorganic Hybrid Perovskite Photosensitive Field‐Effect Transistor Enabled by Poly(3‐Hexylthiophene‐2,5‐Diyl) Channel Layer

Abstract Photosensitive field‐effect transistors (PhFETs) are three‐terminal photodetectors that enable photocurrent modulation and amplification through gate‐voltage control. Organic‐inorganic hybrid perovskites are known for their high photoelectric conversion efficiency, but ion migration in these materials causes gate‐field shielding, posing challenges for constructing PhFETs using only 3D perovskites. To address this issue, a heterojunction strategy is proposed using the stable and process‐compatible organic semiconductor poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as the channel layer and the organic‐inorganic hybrid perovskite cesium‐doped formamidinium lead trihalide (FA _0.9 Cs _0.1 PbI ₃ ) as the light absorption layer. The bottom‐gate top‐contact PhFETs are fabricated using all‐solution processes. By comparing PhFET performance across three active‐layer structures (perovskite, P3HT, perovskite/P3HT) under dark and illuminated conditions, it is found that perovskite devices basically do not exhibit field‐effect but have the highest light‐to‐dark current ratio; P3HT devices exhibit field‐effect but weak photoresponse at 532 nm; in contrast, P3HT/perovskite heterojunction devices not only achieve field‐effect but also exhibit substantial photoresponse. The P3HT channel effectively modulates or amplifies the photocurrent and dark current of the heterojunction device, yielding nearly ten‐fold enhancements in responsivity and external quantum efficiency compared to perovskite devices, along with significantly improved response speed. This study advances the development of 3D organic‐inorganic hybrid perovskite PhFETs.