Cooperative passivation of perovskite solar cells by alkyldimethylammonium halide amphiphiles

Perovskite solar cells (PSCs) have revolutionized the field of sustainable energy research. However, their limited stability has so far impeded commercial exploitation. Here, we present two alkylammonium halide modulators that synergistically improve both power conversion efficiency (PCE) and stability of PSCs based on α-FAPbI3 and FA0.65MA0.35Pb(I0.65Br0.35)3, while also suppressing light-induced halide phase segregation in the latter. Champion PCEs of 24.9% (α-FAPbI3) and 21.2% (FA0.65MA0.35Pb(I0.65Br0.35)3) are reported, with ∼90% and ∼80% of initial PCEs retained after 1,200 and 250 h of continuous operation, respectively. 2D NMR shows that the modulators are located at surfaces and grain boundaries, while their superior passivation effect compared with established compounds is rationalized using computational studies. By addressing the critical issue of stability, our results represent an important step toward large-scale practical applications of PSCs.