Achieving Balanced\nEnergy Harvesting and Light Detection\nvia Compositional Modulation with a High-LUMO-Level Nonfused-Ring\nElectron Acceptor

Organic photovoltaics (OPVs) and\norganic photodetectors\n(OPDs)\noffer promising energy harvesting and photodetection capabilities.\nIn this study, we newly designed and synthesized a novel nonfused-ring\nelectron acceptor (NFREA) named “LK-2” with a high lowest\nunoccupied molecular orbital (LUMO) level of −3.61 eV. We aimed\nto enhance the energy harvesting performance in OPVs by improving\nthe open-circuit voltage (<i>V</i><sub>OC</sub>) and light\ndetecting ability by mitigating the dark currents in the OPDs. LK-2\nwas incorporated into the host photoactive material comprising PM6\ndonors and BTP-4F-12 acceptors using a ternary strategy that facilitated\ncompositional modulation among the materials. The inclusion of LK-2\nresulted in an improved <i>V</i><sub>OC</sub> of 0.84 V\nunder 1-sun illumination and a significantly suppressed dark current\ndensity of 2.77 × 10<sup>–10</sup> A cm<sup>–2</sup> under a self-powered condition. The effective intermixing of LK-2\nwith PM6 and BTP-4F-12 facilitated a favorable thin-film morphology,\ncontributing to enhanced device performance. Furthermore, LK-2 suppressed\nbimolecular recombination under low light intensities and reduced\nnoise currents, resulting in a broad linear dynamic range even under\nreverse bias conditions. This study highlighted the potential of the\nnewly developed NFREA for simultaneously enhancing the performance\nof both OPV and OPD devices, offering a balanced approach to realize\nenergy harvesting and light detection.