High‐Performance Broadband Perovskite Photodetectors Based on CH₃NH₃PbI₃/C8BTBT Heterojunction

Abstract

Perovskite photodetectors are fabricated via structuring a perovskite/organic heterojunction with CH 3 NH 3 PbI 3 and a high‐mobility and stable organic semiconductor dioctylbenzothieno [2,3‐b] benzothiophene (C8BTBT), which possess broad range photoresponse from ultraviolet to near‐infrared, fast response, and excellent stability. The CH 3 NH 3 PbI 3 /C8BTBT heterojunction photodetectors exhibit an excellent ratio of photocurrent to dark current, I light / I dark , as high as 2.4 × 10 4 , a high responsivity up to 24.8 AW −1 , and a fast response of about 4.0 ms. Meanwhile, the photodetectors can maintain 90% performance even exposed in ambient condition without encapsulation for 20 d. In addition, the detailed mechanism is disclosed based on ultraviolet photoemission spectroscopy, steady‐state photoluminescence (PL) spectra, and PL lifetime experiments. The C8BTBT layer acts as an efficient hole‐extraction layer to let the holes quickly transport to the electrodes due to its perfect filling in the gaps between perovskite grains, as well as its intrinsic high mobility and the energy‐level match with the CH 3 NH 3 PbI 3 . The stable C8BTBT layer can well play as a waterproof layer as well to prevent the perovskite CH 3 NH 3 PbI 3 from the degradation. The research provides an excellent method for fabricating high‐performance and stable perovskite photodetectors using perovskite/organic heterojunction.