ITO-free organic solar cell with an PEDOT:PTS/Au/TiO2 grid hybrid electrode as a transparent anode

Abstract

Poly (3, 4-ethylenedioxythophene): p-toluenesulfonate (PEDOT:PTS)/Au/TiO2 grid hybrid structures were investigated to replace indium tin oxide (ITO) electrodes. The effects of TiO2 on the optical properties of PEDOT:PTS/Au and on the critical thickness of Au films at which point the films become electrically continuous were discussed. The multilayer grids were optimized to provide an average transmission of 81% and a sheet resistance of ∼17 Ω/□. In addition, the TiO2 underlayers allowed for the excellent adhesion of the Au grid to a glass substrate. Organic solar cells (OSCs) were fabricated based on PEDOT:PTS(∼70 nm)/Au(12.5 nm)/TiO2 (25 nm) grid hybrid anodes and exhibited an open-circuit voltage of 0.62 V, short-circuit current density of 12.27 mA cm−2, fill factor of 0.51, and power conversion efficiency of 3.88%. These values are comparable to those of ITO-based OSCs. Therefore, PEDOT:PTS/Au/TiO2 grid hybrid structures would be a viable alternative to ITO electrodes for high efficiency organic solar cells.