Covalent bonding strategy to enable non-volatile organic cation perovskite for highly stable and efficient solar cells

The loss of organic components from perovskites has inevitably trig-gered a series of undesirable results, including ion migration, increased defects, and organic vapors, which severely limit the per-formance of perovskite solar cells (PSCs) and impede their progress toward commercial applications. To circumvent this issue, we report a novel covalent bonding strategy by employing bis-diazirine (BD) molecules to covalently bond organic cations of perovskites. Exper-imental and ab initio simulation results confirmed the efficacy of BD molecules to strongly immobilize the organic cations and eventually enhance the thermal, illumination, and electrical bias resistance properties of perovskites. Consequently, highly efficient (24.36% efficiency, certified 24.02%) and ultra-stable PSCs were realized, which retained 98.6% of their initial efficiency even after 1,000 h of operational tests.