Interface modification using a post-treatment-free heteropolyacid for effective charge selective bilayer formation in perovskite solar cells

We rationally utilized a solution-processed post-heat treatment-free heteropolyacid compound, phosphomolybdic acid hydrate (PMAH) as a charge selective interface modifier for poly(3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT:PSS) in inverted perovskite solar cells (PSCs). The fabricated PSCs with PMAH/PEDOT:PSS bilayer exhibited significant improvement in the power conversion efficiency (PCE) (∼12%) with superior long-term air-stability as compared to PEDOT:PSS based PSCs (9.8%). The measured photovoltaic performance demonstrates that the inclusion of PMAH as an interface to ITO and PEDOT:PSS is an efficient way of realizing stable and efficient PSCs.