Development of Air‐Stable Photomultiplication‐Type Organic Photodetector and Analysis of Active Layer using Removable Top Electrode

Abstract Organic photodetectors (OPDs) are preferred for use in biological sensing applications owing to their mechanical flexibility and good optical characteristics. To enhance the sensitivity of OPDs, a photomultiplication‐type OPD (PMOPD), which can produce amplification at two terminals, has been developed. However, the stability of this photodetector is an issue when it is used in image sensors or other applications. In this study, an air‐stable PMOPD with a PBDTTT‐OFT:PC 61 BM active layer that has high responsivity in the near‐infrared region is developed. Furthermore, an OPD with a removable top electrode has been developed. Using this new device structure, the authors can directly and continuously evaluate the active layer of the device after using it in the air. It has been observed that the device does not exhibit any chemical changes in the active layer.