Alcohol solvent treatment of PEDOT:PSS hole transport layer for optimized inverted perovskite solar cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely used as a hole transport materials in perovskite solar cells, due to a variety of suitable properties. However, the existence of the insulated PSS chain leads to the low electrical conductivity, which should be improved for the further development of inverted perovskite solar cells. In this study, three alcohol solvents were proposed for post-treatment of PEDOT:PSS thin films, which utilized the electrostatic shielding effect of alcohol molecules to promote phase separation of the PEDOT chain and the PSS chain. At the same time, The insulated PSS chain was removed by dissolving in highly hydrophilic alcohols. In the end, we successfully improved the conductivity of PEDOT:PSS thin films. By ethanol solvent treatment, the short-circuit current density of the perovskite solar cell based on glass/ITO/PEDOT:PSS was increased from 15.64 to 17.45 mA/cm2, the power conversion efficiency (PCE) reached 11.36%, which was 25% higher than the traditional structure. For flexible devices, a preliminary PCE of 9.20% was achieved.