MoO3/Au/MoO3–PEDOT:PSS multilayer electrodes for ITO-free organic solar cells

The effect of the MoO3–PEDOT:PSS composite layer in the MoO3/Au/MoO3–PEDOT:PSS multilayer electrode on the power conversion efficiency of ITO-free organic solar cells (OSCs) was evaluated. The MoO3 (30 nm)/Au(12 nm)/MoO3–PEDOT:PSS (30 nm)/PEDOT:PSS structure showed ~7% more optical transmittance than the MoO3 (30 nm)/Au (12 nm)/MoO3(30 nm)/PEDOT:PSS structure at 550 nm wavelength. The OSCs using MoO3/Au/MoO3–PEDOT:PSS multilayer electrodes as anodes showed a considerable improvement in power conversion efficiency (PCE), from 1.84% to 2.81%, comparable to ITO based OSCs with PCE of 2.89%. This improvement is attributed to the suppression of MoO3 dissolution by the acidic hole transport layer (HTL) PEDOT:PSS on the MoO3/Au/MoO3–PEDOT:PSS multilayer electrode, resulting in high Jsc, Voc and FF of the OSCs. This composite based multilayer electrode was shown to be a promising replacement in ITO-free flexible optoelectronic devices.