Stabilizing Perovskite Precursor by Synergy of Functional Groups for NiO x -Based Inverted Solar Cells with 23.5 % Efficiency.

Perovskite solar cells suffer from poor reproducibility due to the degradation of perovskite precursor solution. Herein, we report an effective precursor stabilization strategy via incorporating 3-hydrazinobenzoic acid (3-HBA) containing carboxyl (-COOH) and hydrazine (-NHNH 2 ) functional groups as stabilizer. The oxidation of I - , deprotonation of organic cations and amine-cation reaction are the main causes of the degradation of mixed organic cation perovskite precursor solution. The -NHNH 2 can reduce I 2 defects back to I - and thus suppress the oxidation of I - , while the H + generated by -COOH can inhibit the deprotonation of organic cations and subsequent amine-cation reaction. The above degradation reactions are simultaneously inhibited by the synergy of functional groups. The inverted device achieves an efficiency of 23.5 % (certified efficiency of 23.3 %) with an excellent operational stability, retaining 94 % of the initial efficiency after maximum power point tracking for 601 hours.