Transparent conductive oxide-free perovskite solar cells with PEDOT:PSS as transparent electrode.

Perovskite solar cells (PSCs) have been attracting considerable attention because of their low fabrication cost and impressive energy conversion efficiency. Most PSCs are built on transparent conductive oxides (TCOs) such as fluorine-doped tin oxide (FTO) or indium tin oxide (ITO), which are costly and rigid. Therefore, it is significant to explore alternative materials as the transparent electrode of PSCs. In this study, highly conductive and highly transparent poly(3,4-ethylenedioxythiophene):polystyrenesulfonate ( PEDOT: PSS) films were investigated as the transparent electrode of both rigid and flexible PSCs. The conductivity of PEDOT: PSS films on rigid glass or flexible poly(ethylene terephthalate) (PET) substrate is significantly enhanced through a treatment with methanesulfonic acid (MSA). The optimal power conversion efficiency (PCE) is close to 11% for the rigid PSCs with an MSA-treated PEDOT: PSS film as the transparent electrode on glass, and it is more than 8% for the flexible PSCs with a MSA-treated PEDOT: PSS film as the transparent electrode on PET. The flexible PSCs exhibit excellent mechanical flexibility in the bending test.