[12p-N207-1~16] 12.3 Functional Materials and Novel Devices

▼ [12p-N207-15] Improvement of dark current stability of ZnO-based organic photodiode by control of annealing condition

〇Theodorus Jonathan Wijaya¹, Mari Koizumi¹, Sunghoon Lee¹, Tomoyuki Yokota¹, Takao Someya¹ (1.Dept. of EEIS, The Univ. of Tokyo)

Keywords:organic photodiode, dark current, flexible electronics

Dark current in organic photodiodes (OPDs), a dominating factor of noise density, is well-known for its increase upon illumination of strong light. Recently, the mechanism of this instability in OPD with ZnO electron transfer layer was reported [J. Huang et al., ACS Nano 15, 1753 (2021)]. However, the strategy to suppress the dark current increase in ZnO-based OPDs remains unexplored. Here, using an inverted structure of bulk heterojunction OPDs, we demonstrated that the dark current increase can be suppressed by control of annealing temperature (T_anneal). The devices with structure: glass/ITO (70 nm)/ZnO (30 nm)/P3HT:PC₆₁BM (250 nm)/MoO_x (10 nm)/Ag were fabricated using spin coating and a standard evaporation system. We successfully decreased the ratio of dark current density after illumination to its initial value from 1.0x10² to 0.64 by raising T_anneal from 180 to 350^oC. Our results provide insights into the importance of annealing conditions to the dark current stability.