Haze-enhanced ZnO/Ag/ZnO nanomesh electrode for flexible, high-efficiency indoor organic photovoltaics

Abstract

An oxide/metal/oxide multilayer electrode is employed to improve the mechanical flexibility as well as power conversion efficiency of organic photovoltaics. However, its performance needs to be further improved to provide a higher conversion efficiency and better environmental compatibility with curved indoor electronics. In this study, ZnO/Ag/ZnO nanomesh electrodes are incorporated into the inverted non-fullerene organic photovoltaics to enhance the efficiency under indoor and outdoor lighting illumination in a flexible mode. The opto-electrical properties of the perforated ZnO/Ag/ZnO nanomesh electrode with different hole sizes are compared with those of the planar ZnO/Ag/ZnO and indium tin oxide electrodes. The micro-cavity effect and haze effect, which plays a crucial role in determining the performance of the organic photovoltaics, are directly related to the hole diameter. Despite higher transmittance of indium tin oxide, organic photovoltaics using ZnO/Ag/ZnO nanomesh electrodes with a hole diameter of 350 nm exhibits an average conversion efficiency of 15.7% under a 1000 lux light-emitting diode lamp; this efficiency is 45.3% and 27.6% greater than those of organic photovoltaics using indium tin oxide and planar ZnO/Ag/ZnO electrodes, respectively. Furthermore, all ZnO/Ag/ZnO nanomesh-based organic photovoltaics show much higher mechanical flexible properties than those of the planar ZnO/Ag/ZnO-based organic photovoltaics. • ZnO/Ag/ZnO nanomesh is employed as a cathode for flexible organic photovoltaics. • Opto-electrical properties of the ZnO/Ag/ZnO nanomesh electrode are optimized. • As the hole size decreases, optical haze and micro-cavity effect are found to increase. • Fabricated photovoltaic shows a 15.7% efficiency under 1000 lux LED light. • Fabricated photovoltaic also exhibits an excellent mechanical flexibility.