Researchers from China's Westlake University, Advanced Solar Technology Institute of Xuancheng and Turkey's Marmara University have addressed the stability issues of perovskite solar cells (PSCs) by developing a divalent cation replacement strategy that mitigates ionic migration while limiting phase segregation.
Using the new method, the scientists fabricated a champion cell that showed a PCE of 23.20% (certified 22.71%) for a single-junction PSC with a bandgap between 1.67 eV and 1.68 eV. Furthermore, a PCE of 30.13% was obtained for mechanically stacked perovskite/Cu(In,Ga)Se2 tandem devices, and a PCE of 21.88% for transparent perovskite devices. Finally, they obtained a steady-state PCE of 23.28% (certified 22.79%) for flexible monolithic perovskite/Cu(In,Ga)Se2 tandem cells.
The team explained that the replacement of the A-site cations in the perovskite lattice with methylenediammonium cations (MDA2+) substantially suppresses the issues that impede stability in wide-bandgap perovskites. This is mainly due to the bivalent state of MDA2+ generating a strong interaction with the inorganic framework and reducing the mobility of halide ions and the formation of defects. As a result, the stability and efficiency of the fabricated PSCs are substantially improved.
