Enhanced crystallization and stability of perovskites by a cross-linkable fullerene for high-performance solar cells

Organic-inorganic halide perovskite solar cells (PSCs) still suffer from the issues of poor reproducibility and inferior stability despite their considerable increase in efficiency. Here, we demonstrate planar PSCs with simultaneously improved device characteristics and stability by introducing a cross-linkable [6,6]-phenyl-C-61-butyric styryl dendron ester (PCBSD) into CH3NH3PbIxCl3-x perovskites. The cross-linkable merit of C-PCBSD can enhance the crystallization of perovskites and address the issue of low electron extraction efficiency. In addition, the anti-solvent network of C-PCBSD facilitates the sequential solution process and prevents washing by the solvent used in the upper layer. The C-PCBSD network resisted the moisture incursion and protected the interfaces from erosion, and it passivated the voids or pinholes generated in the bulk active layer. As a result, an outstanding PSC with a power conversion efficiency of 17.21% is achieved with evidently improved cell stability.