Enhancing performance of inverted planar perovskite solar cells by argon plasma post-treatment on PEDOT:PSS

Interface engineering is an efficient method for improving the performance of inverted planar heterojunction perovskite solar cells (PSCs). In this paper, the PSCs were modified by introducing mild argon plasma post-treatment on poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS). The power conversion efficiency (PCE) was enhanced up to 12.17%, compared with 9.55% of the reference device without interlayer modification. We found that argon plasma treatment on the PEDOT: PSS layer effectively increases its conductivity due to the modification of the PSS ratio in the film. The argon plasma treatment time directly affects the surface morphologies and contact angles of the PEDOT: PSS layer and therefore optimises the uniformity of the PEDOT: PSS layer on the nanometer-scale. The improvement in the chemical compositions and film morphologies of PEDOT: PSS could be beneficial to enhancing the wettability and retarding the carrier recombination. The open-circuit voltage (V-oc) and short circuit current density (J(sc)) of PSCs based on the treated PEDOT: PSS were both improved, resulting in the enhancement of PCE.