[23a-C105-1~11] 12.3 Functional Materials and Novel Devices

▼ [23a-C105-2] Revealing effects of illumination wavelength on the dark current increase of organic photodiodes with ZnO electron transport layer

〇(M2)Theodorus Jonathan Wijaya¹, Yokota Tomoyuki¹, Lee Sunghoon¹, Okano Ryo¹, Kobayashi Masaki¹, Someya Takao¹ (1.UTokyo EEIS)

Keywords:organic photodiodes, electron transport layers, photostability

Efforts to improve responsivity and reduce dark current have resulted in high-detectivity organic photodiodes (OPDs). However, OPDs with ZnO electron transport layer (ETL) suffer from a photoinduced increase of reverse dark current, impeding the realization of a reliable photodetection. Previously, we reported how higher-temperature annealing of the ZnO ETL can suppress such instability. Here, we systematically investigated the effects of illumination conditions on the dark current increase in OPDs with ZnO ETL, revealing that increases at wavelengths longer than 380 nm are much lower than and at most 17.6% of those observed at sub-370-nm illuminations. Employing OPDs with a “glass/ITO/ZnO/P3HT:PC₆₁BM/MoO_x/Ag” structure, we confirmed the reproducibility of the finding. In addition, by examining the role of defects in ZnO ETLs, we elucidated the mechanism behind the instability. These results provide insights into the design requirements of a photostable OPD with reliable detectivity.