Suppressing Shunt and Trap-Assisted Recombination in Organic Photovoltaic Devices For Improved Indoor Light Harvesting Efficiency

Abstract

Performance losses in indoor organic photovoltaic (OPV) devices, particularly those processed with nonhalogenated solvents, remain significant under weak illumination conditions, posing challenges for their integration with electronic technologies. In this study, the performance losses in indoor OPV devices processed with a nonhalogenated solvent are investigated. Indoor OPV devices based on the wide-bandgap acceptor F-BTA3, optimized to respond to the wavelength of white-light-emitting diode (LED) light, are constructed. It is found that device performance deteriorates as illumination intensity decreases below 1000 lx. Through device physics analysis, it is identified that the performance decline is primarily attributed to low shunt resistance (R_sh) and high trap state density. A solid additive strategy is then employed, and its impact on R_sh is examined, resulting in a reduction in the leakage current density (J_leak) and improved device performance under low illumination conditions. Additionally, a nonhalogenated solvent mixing method is developed, which, in combination with the solid additive strategy, enhances R_sh and reduces trap-assisted recombination losses, further improving device performance under low illumination conditions.