Improving Performance of Organic Photovoltaic Devices under Low Illuminations

Organic photovoltaic (OPV) devices have garnered substantial interest due to their appealing ability to tailor the optical properties of organic active materials, rendering them highly promising for efficient energy conversion even under low lighting conditions. Nevertheless, the performance of OPV devices under low illumination intensities remains a challenge, often resulting in power conversion efficiencies that fall notably below theoretical predictions. In this study, we elucidate that the restricted performance of OPV devices under weak illumination intensities is linked to the presence of substantial voltage losses. Particularly, elevated nonradiative voltage losses, stemming from charge carrier recombination facilitated by traps, emerge as a primary factor. To address the pivotal concern of trap-assisted recombination losses, we propose a 2-fold strategy involving acceptor side chain modification and the utilization of a high-boiling-point solvent. By strategically modifying the molecular structure of the electron acceptor and optimizing the processing conditions of the active layer, the performance of OPV devices characterized by low illumination intensities witnesses a remarkable enhancement. This innovative approach not only mitigates the constraints imposed by trap-assisted recombination losses but also empowers the OPV devices to efficiently harness low lighting conditions.