Design of broadband transparent electrode for flexible organic solar cells

Abstract

Broadband transparent electrodes, Ta2O5/Ag/WO3-x, are successfully designed to enhance light absorption and carrier transport properties in organic solar cells (OSCs) as an alternative to ITO/PEDOT:PSS. Employing the optical constants matching layer, zero reflection condition could be achieved over a broad range of wavelengths. Moreover, the non-stoichiometric WO3-x could induce a large density of gap states near the Fermi level via quick thermal deposition, acting as carrier transport path. Significantly improved current densities were achieved, increasing the power conversion efficiency from 2.1 % to 2.9 % which values are comparable to conventional ITO device.