An alcohol-dispersed conducting polymer complex for fully printable organic solar cells with improved stability

Efficient and stable organic solar cells via full coating are highly desirable. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a classic conducting polymer complex and widely used for hole collection in fully printable devices. However, PEDOT:PSS is typically dispersed in water and exhibits strong acidity that deteriorates device efficiency and stability. Here we report an alcohol-dispersed formulation (denoted as PEDOT:F) by adopting perfluorinated sulfonic acid ionomers as counterions. The ionomers have a special advantage of having two solubility parameters and can be dispersed in water or alcohols, which enables us to prepare PEDOT:F formulations dispersed in alcohols. The alcohol-dispersed formulation has good wetting properties and low acidity, which avoids the drawbacks of aqueous PEDOT:PSS. Fully printable organic photovoltaics (from bottom electrode to top electrode) based on PEDOT:F were obtained with a power conversion efficiency of 15% and could retain 83% of the initial efficiency under continuous illumination at maximum power point tracking for 1,330 h.