Fluorinated fused nonacyclic interfacial materials for efficient and stable perovskite solar cells

Three fused-ring n-type semiconductors based on 6,6,12,12-tetrakis(4-hexylphenyl)-indacenobis(dithieno [3,2-b; 2,3-d] thiophene) end-capped with 1,1-dicyanomethylene-3-indanone substituted by different numbers of fluorine atoms (INIC series) are employed as interfacial materials to modify the surface of the perovskite film in inverted planar perovskite solar cells (PSCs). Due to fast interfacial charge extraction and efficient trap passivation, PSCs based on INIC series exhibit a maximum power conversion efficiency of 19.3% without any hysteresis, which is superior to control devices without INIC series (16.6%). Moreover, the strong water-resistance ability of fluorinated INIC significantly enhances the ambient stability of the PSCs. The effects of fluorine atom number on the device performance are discussed.