Synergetic defect passivation of high‐quality 1.83  <scp>eV</scp> perovskite for efficient flexible perovskite/organic tandem photovoltaics

Abstract Light‐weight, flexible perovskite/organic tandem solar cells (TSCs) hold great potential for applications in wearable electronics, agricultural photovoltaics, building‐integrated photovoltaics, car‐integrated photovoltaics, and other emerging applications. However, matching current densities of near‐infrared organic absorbers typically requires wide‐bandgap (WBG, >1.80 eV) perovskites, which suffer from complex compositions, uncontrolled defect formation, and severe nonradiative recombination. Herein, we propose a rationally designed synergistic ionic additive, (R)‐(+)‐tetrahydro‐3‐furylamine p ‐toluenesulfonate salt, where both the cation and anion are engineered to deliver complementary defect passivation effects. Specifically, the p ‐toluenesulfonate anion and the (R)‐(+)‐tetrahydro‐3‐furylamine cation can form electrostatic interactions with various defects, while their functional groups can further enhance the passivation effect by strong interactions. The corresponding characterizations further reveal that this synergistic defect modulation strategy enables comprehensive defect passivation, residual stress relaxation, and mechanical robustness enhancement in WBG perovskite films. As a result, our WBG perovskite solar cells and perovskite/organic TSCs on flexible substrates achieve power conversion efficiencies of 18.13% and 22.44%, respectively, along with excellent mechanical bending stability. image