In this study, we demonstrate inâsitu nâdoping and crosslinking of semiconducting polymers as efficient electronâtransporting materials for inverted configuration polymer solar cells. The semiconducting polymers were crosslinked with bis(perfluorophenyl) azide (bisâPFPA) to form a robust solventâresistant film, thereby preventing solventâinduced erosion during subsequent solutionâbased device processing. In addition, chemical nâdoping of semiconducting polymers with (4â(1,3âdimethylâ2,3âdihydroâ1Hâbenzoimidazolâ2âyl)phenyl)dimethylamine (NâDMBI) substantially improved the power conversion efficiency of solar cells from 0.69% to 3.42%. These results open the way for progress on generally applicable polymeric interface materials, providing not only high device performance but also an effective fabrication method for solutionâprocessed multilayer solar cell devices.