Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)–molybdenum oxide composite films as hole conductors for efficient planar perovskite solar cells

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)–molybdenum oxide (MoO_x) composite films are used as hole transport layers in planar perovskite solar cells (PSCs) by simply incorporating solution-processed MoO_x powders into a PEDOT:PSS solution. Compared to PEDOT:PSS based PSCs, the PEDOT:PSS–MoO_x based PSC exhibits an obvious improvement in conversion efficiency, open circuit voltage, and fill factor. The morphology of perovskite films indicates that the film coverage has been improved due to the introduction of MoO_x nanospots into the underlayer, which are regarded as the growing sites of the crystal nucleus of the perovskites during annealing. A PEDOT:PSS–MoO_x based device with a power conversion efficiency of over 15% has been achieved, suggesting that the PEDOT:PSS–MoO_x film is efficient as a hole transport layer in obtaining highly efficient planar perovskite solar cells.