Enhanced stability and efficiency in inverted perovskite solar cells through graphene doping of PEDOT:PSS hole transport layer

Poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) plays a relevant role in the device performance as hole extraction layer (HTL) of inverted perovskite solar cells. Here, we show a simple low-temperature spin coating method for obtaining homogenous graphene-doped thin films of PEDOT:PSS with improved electrical conductivity without decreasing optical transmittance. Moreover, the crystallinity and stability in ambient conditions of the perovskite grown on it are enhanced. The hydrophobic character of graphene probably blocks undesirable reactions hampering degradation. By impedance spectroscopy it is demonstrated better charge extraction and reduction of recombination mechanisms at the doped-HTL/perovskite interface, resulting in improved photovoltaic parameters of the solar cell and greater stability at room operation conditions thus providing a simple and cost-effective method of preparing solar cells based on hybrid perovskites. [Display omitted] •Addition of graphene platelets into PEDOT:PSS layers improves up to 10 times its conductivity, maintaining the transmittance.•MAPbI3 film grown on graphene-doped PEDOT:PSS exhibits large crystallite size and lower PbI2 content, leading high stability.•Inverted solar cells based on graphene-doped PEDOT:PSS show better photovoltaic parameters by increasing charge extraction.