A crosslinked fullerene matrix doped with an ionic fullerene as a cathodic buffer layer toward high-performance and thermally stable polymer and organic metallohalide perovskite solar cells

In this study, we developed a new cathodic buffer layer consisting of a cross-linked [6,6]-phenyl-C-61-butyric styryl dendron ester (C-PCBSD) matrix and an ionic FPI dopant. The incorporation of FPI can improve the electron mobility via an anion induced charge transfer (AIET) mechanism, while maintaining the solvent-resistant properties of the crosslinked layer. ZnO combined with the C-PCBSD/FPI layer can effectively and universally improve the performance of bulk-heterojunction polymer solar cells (BHJPSCs), planar heterojunction polymer solar cells (PHJPSCs), and organic metallohalide perovskite solar cells (OMPSCs). Furthermore, the insertion of the C-PCBSD/FPI layer can improve the thermal stability of the device by preventing the residual moisture in ZnO from diffusing into the CH3NH3PbI3 layer in OMPSCs.