Reduction of Nonradiative Recombination at Perovskite/C₆₀ Interface in Inverted Perovskite Solar Cells

Although p-i-n type inverted perovskite solar cells (PSCs) achieve excellent photoelectric efficiencies, the nonradiative recombination at the perovskite/C₆₀ interface is still the key factor affecting the overall efficiency of p-i-n PSCs. Herein, a synergistic passivation strategy (meta-fluoro-phenylethylammonium iodide and piperazine iodide) is developed to modify the perovskite/C₆₀ interface in p-i-n PSCs. This strategy facilitates in situ reconstruction of the perovskite film to obtain a smooth and flat perovskite surface. Furthermore, the two molecules work synergistically to passivate surface defects, adjust the interface energy levels, and bolster the interface electric field, all of which reduce the nonradiative recombination losses at the perovskite/C₆₀ interface. The optimal PSCs adopting this strategy achieve a power conversion efficiency of 25.85%. (certified value of 25.22%). After operating at the maximum power point for 1000 h, the 95% initial efficiency can be maintained. Furthermore, this process is universally applicable and scalable.