Fully solution-processed n-i-p type perovskite solar cells with efficiency over 19% enabled by a hydrophobic PEDOT:F interlayer and silver nanowire top electrode

Solution-processed top electrode is the key technology for the realization of fully solution-processed perovskite solar cells (PSCs). In this paper, we reported the preparation of fully-solution processed n-i-p type PSCs with spray-coated silver nanowires (AgNWs) top electrode. Experiment results demonstrated that low power conversion efficiency (PCE) of 16.00% with a low fill factor of 67.41% was obtained for the reference cell, when the AgNWs is directly coated on the 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9 '-spirobifluorene (Spiro-OMeTAD) layer. This result indicates a charge extraction barrier at the Spiro-OMeTAD/AgNWs interface, which could be attributed to the poor compatibility between Spiro-OMeTAD and AgNWs layers. By inserting a thin layer of poly(3,4-ethylenedioxythiophene):perfluorinated sulfonic acid ionomers (PEDOT:F), a modified PEDOT with lower surface energy, the interface connection between Spiro-OMeTAD/PEDOT:F and AgNWs was improved, leading to an enhanced PCE of up to 19.11%. In addition, the PEDOT:F-based cells retained 64% of the initial PCE after operating at the maximum power point for 1800 h, whereas the reference cells retained only 30% of the initial PCE. The current work proved that PEDOT:F/AgNWs could be an excellent option for fully-solution processed n-i-p type PSCs.