Revealing the Effect of Ionic Traps on Photovoltaic Performance of Organic Semiconductor Materials

Abstract

Organic semiconductor materials possess unique advantages in various photoelectric applications. Due to the complicated preparation processes, many impurities are difficult to remove and become extrinsic traps in materials. However, there exists almost no relevant research on the effects of extrinsic traps on the performance of organic semiconductor materials. In this work, we comprehensively investigate the impacts of ionic traps based on organic photovoltaic (OPV) cells. We demonstrate that the different effects of impurities result from their ionization ability in processing solvent. The ionic traps can induce increased density of trap states and severe trap-assist recombination, thereby deteriorating device performance. In addition, we propose a simple method to evaluate the quality of organic semiconductor materials through electrochemical impedance spectroscopy. This research facilitates the batch preparation of organic semiconductor materials and the industrialization of OPV cells.