Affiliation:
1. Department of Physics Faculty of Science and Technology University of Nairobi (UoN) P.O. Box 30197‐00100 Nairobi 00100 Kenya
2. Advanced Energy Materials Research Center Korea Research Institute of Chemical Technology (KRICT) Daejeon 34114 Republic of Korea
3. Advanced Materials and Chemical Engineering University of Science and Technology (UST) Daejeon 34113 Republic of Korea
Abstract
The most widely used material in electron transport layers (ETL) of inverted organic solar cells (iOSCs) is zinc oxide (ZnO). However, the brittleness, inorganic nature, surface defects, and photocatalytic activity of ZnO lead to poor stability in iOSCs. Herein, the light‐soaking and thermal stability of iOSCs are substantially improved by modifying ZnO surface with polyurethane diacrylate (SAR) or urethane acrylate (OCS)‐based ultraviolet (UV) resins. The UV resins significantly reduce the energy barrier, suppress surface defects, and improve interfacial contact between ZnO ETL and the organic photoactive layer. Notably, the SAR and OCS resins mitigate the photocatalytic activity of ZnO, electrical leakage, and interfacial resistance during photoaging of OSCs. As a result, iOSCs based on modified ZnOs retain over 80% of initial efficiency under 1 sun illumination for light soaking 1000 h. Furthermore, SAR and OCS resins on ZnO surfaces form a robust crosslinked network with excellent solvent resistant properties, which result in enhanced thermal stability. These results reveal that this simple and effective approach is a promising procedure to fabricate high‐performance iOSCs.