Enhanced Detectivity and Electrical Properties in Organic Photodetectors Using IGZO Interfacial Layer

Organic photodetectors (OPDs) offer advantages such as flexibility, being light in weight, and cost-effectiveness relative to their silicon-based counterparts. However, challenges like high leakage current, slow response time, and low stability limit their performance. In this study, we propose the utilization of sol–gel synthesized indium gallium zinc oxide (IGZO) doped with different metal ratios as a hole-blocking layer to suppress carrier collection and reduce leakage current. We further investigate its impact on OPD performance. Our results demonstrate that the IGZO layer reduced the leakage current by approximately 265-fold relative to the undoped zinc oxide (ZnO) at −2 V and mitigated the degradation of the detectivity (D*) under reverse bias. Impedance analysis further confirmed that the variation in the leakage current under reverse bias correlates with changes in the resistance components due to the doping ratios, and that the increased metal doping of IGZO not only reduces the leakage current but also enhances the conductivity of the individual thin films. These findings indicate that sol–gel-processed IGZO could be applied to various solution-processed devices other than OPD applications.