Improving photostability of non-fullerene acceptor-based inverted organic solar cells using Ga-doped ZnO electron transport layer

Abstract

Organic solar cells (OSCs) are gaining attention for powering Internet of Things devices due to their impressive power conversion efficiency, flexibility, and slim designs suitable for both indoor and outdoor. The focus on inverted-structured OSCs is increasing due to their superior stability compared to conventional OSCs. This study investigates the use of inverted OSCs with electron transport layers (ETL) made from ZnO and Ga-doped ZnO for light harvesting. OSCs were fabricated using PM6:ITIC-4F as the active layer, and the impact of ZnO doping (Ga) concentration was examined under 1-sun and 1000 lx halogen. Optimizing the doping concentration significantly improved device performance, with PCE values of 10.96 % and 4.95 % for optimally doped ZnO under 1-sun conditions and halogen lamps, respectively. A comparison of photostability under 1-sun and 1000 lx halogen, with varying light soaking durations (0–240 min), showed that Ga-doping in the ZnO ETL improved photostability by reducing oxygen vacancies and slowing down their formation during continuous light exposure. This decrease in oxygen vacancies and enhancement of grain boundaries positively affected charge transport, leading to higher PCE. In summary, Ga-doped ZnO ETL in inverted OSCs demonstrates improved performance and photostability, making them promising for various light harvesting applications.