Near-infrared-II photodetection realized by introducing organic-inorganic charge-transfer-complex photosensitive material into pentacene phototransistor

Organic phototransistor (OPT) is a promising photodetector with substantial attention due to its advantages such as low cost, light weight, flexibility and ease of large area preparation. Although the second near-infrared (NIR-II) window (1.0–1.7 μm) has important applications in fiber communication, the organic infrared photosensitive materials are scarce in this waveband, which greatly limits the application of organic photodetectors in near-infrared bands. In this work, a charge-transfer-complex (CTC) film with significant hyperchromic effect in the infrared range of 1000–1400 nm was prepared by co-evaporation of metal oxide WO3 and organic molecule m-MTDATA. A high performance near-infrared OPT was fabricated by combining this CTC photosensitive layer and pentacene (PENT) high-mobility channel layer, the photoresponsivity R of which has surpassed the recent reported level of 1.1 μm band inorganic infrared detector. The physical mechanism underlying the operation of CTC-PENT-OPT was clarified and the thickness of the CTC photosensitive film in this device was optimized. This new type of organic-inorganic CTC infrared-sensitive material will offer a new choice for the future study on organic infrared detectors.