Low‐Temperature Prepared ZnO Layer with Electron Beam Annealing Process for Enhancing the Environmental, Thermal, and Operational Stability of Organic Photovoltaics

Abstract

The commercialization of organic photovoltaics (OPVs) requires a high level of stability and a high‐power conversion efficiency (PCE). To satisfy these requirements, inverted OPVs with electron transport layers of ZnO obtained by electron beam annealing (EBA) are fabricated, and their properties are compared with those of a reference device with a thermal‐treated ZnO layer. Electrons are extracted from Ar plasma and accelerated by supplying a negative DC voltage; the ZnO layer is annealed using the energy from the accelerated electrons. The PCE of the OPV with a ZnO layer obtained by the optimal EBA process is 15.6%, which is 11.4% higher than that of the reference device. In addition, the OPV device retains 90.1% of its initial PCE after it is stored at room temperature for 30 days and 70.1% of the initial PCE after 280 h at 90 °C. Further, the operational stability is measured for 500 min at the maximum power point under 1 sun illumination in ambient air. The OPV with the ZnO layer treated under optimal EBA conditions retains 85.0% of the initial PCE and shows outstanding environmental and thermal stability.