Achieving Balanced Energy Harvesting and Light Detection via Compositional Modulation with a High-LUMO-Level Nonfused-Ring Electron Acceptor

Abstract

Organic photovoltaics (OPVs) and organic photodetectors (OPDs) offer promising energy harvesting and photodetection capabilities. In this study, we newly designed and synthesized a novel nonfused-ring electron acceptor (NFREA) named “LK-2” with a high lowest unoccupied molecular orbital (LUMO) level of −3.61 eV. We aimed to enhance the energy harvesting performance in OPVs by improving the open-circuit voltage (V_OC) and light detecting ability by mitigating the dark currents in the OPDs. LK-2 was incorporated into the host photoactive material comprising PM6 donors and BTP-4F-12 acceptors using a ternary strategy that facilitated compositional modulation among the materials. The inclusion of LK-2 resulted in an improved V_OC of 0.84 V under 1-sun illumination and a significantly suppressed dark current density of 2.77 × 10^–10 A cm^–2 under a self-powered condition. The effective intermixing of LK-2 with PM6 and BTP-4F-12 facilitated a favorable thin-film morphology, contributing to enhanced device performance. Furthermore, LK-2 suppressed bimolecular recombination under low light intensities and reduced noise currents, resulting in a broad linear dynamic range even under reverse bias conditions. This study highlighted the potential of the newly developed NFREA for simultaneously enhancing the performance of both OPV and OPD devices, offering a balanced approach to realize energy harvesting and light detection.