Inverted organic photovoltaics using highly transparent and flexible InGaON/AgTi/InGaON multilayer electrodes

The inverted organic solar cell (IOSC) supported on an optically transparent and mechanically flexible oxynitride/metal/oxynitride substrate is receiving increasing attention owing to its light weight, flexible, and cost-effective design, compared to the conventional oxide-based solar cells. To develop an efficient IOSC, technical issues related to charge carrier transport and the transmittance of the conventional oxide electrode need to be solved. Herein, we report a highly transparent cathode for a highly efficient inverted organic solar cell using InGaON/Ag–Ti/InGaON multilayer electrodes. The In ₂O ₃ and GaN targets are co-sputtered to fabricate the multicomponent conductive oxynitride films. The sheet resistance of InGaON in optimized sputtering conditions is about 53.63 Ω/□, with the transmittance of 88.12%. The optimal InGaON/Ag–Ti/InGaON configuration (35/12/35 nm) showed the low sheet resistance of 5.7 Ω/□, and higher transmittance of about 96.8% as a whole InGaON/Ag–Ti/InGaON electrode. The multilayer electrode showed superior mechanical property in bending and twisting for 10,000 cycles with no resistance change. Furthermore, the inverted organic solar cell with the deposited layers of InGaON/Ag–Ti/InGaON–ZnO–Active layer–MoO ₃–Ag exhibited the higher power conversion efficiency of 8.63%, indicating that the InGaON/Ag–Ti/InGaON cathode is a promising candidate for substitution for the conventional oxide electrode.