Mitigation of Illumination Sensitive Dark Current in Broadband Organic Photodiode Enabled by Robust Interface Engineering

Abstract

The reliability of performance metrics in organic photodiodes (OPDs) is a fundamental factor for their efficacy in real-time applications. Among these metrics, the dark current density stands out for its direct impact on the sensitivity of the detectors. In this study, an anomalous illumination-sensitive variation in dark current is observed in fabricated near-infrared OPDs, which undermines the device reliability. The systematic investigation reveals that this behavior stems from the photocatalytic nature of zinc oxide (ZnO), the electron transport layer used in the OPD. The photocatalytic nature of ZnO detrimentally affects the stability of the active material, particularly the nonfullerene acceptor employed in this study. Through robust interface engineering approach, which involves modifying the interface between ZnO and the active layer, the anomalies in the dark current are successfully mitigated, enhancing the consistency and reliability of the OPDs. In addition to reducing the dark current, this interface engineering strategy improves the overall performance and operational stability of the OPDs, especially under ultraviolet exposure.