Buffer and anode-integrated WO₃-doped In₂O ₃ electrodes for PEDOT:PSS-free organic photovoltaics

We developed PEDOT:PSS-free organic solar cells (OSCs) using WO₃ and In₂O₃ (IWO) mixed electrodes acting as a buffer hole injection layer (HIL) and anode simultaneously. Through the co-sputtering and rapid thermal annealing (RTA) of WO₃ and In₂O₃, we achieved buffer and anode-integrated transparent electrodes with a sheet resistance of 17 Ohm/square, a transmittance of 90.32%, and a work function of 4.83 eV, all of which are comparable to values obtained with a conventional ITO anode. Due to the existence of WO₃ in the In₂O₃ matrix, OSCs fabricated on an IWO electrode with no acidic PEDOT:PSS buffer layer showed a PCE of 2.87%. Therefore, a transparent IWO electrode simultaneously acting as an HIL and anode layer can be considered a promising transparent electrode for cost-efficient and reliable OSCs because it could eliminate the use of acidic PEDOT:PSS buffer layer.