Hydrazine derivative-based surface passivator for efficient and stable perovskite solar cells

Despite many efforts, it is still challenging to realize perovskite solar cells (PSCs) that satisfy both high efficiency and long-term stability. Eliminating or suppressing defects present at the perovskite surface and grain boundaries (GB) is crucial to improve the efficiency and extend the operating lifetime of PSCs. From this perspective, in this work, a functional molecule, 4-hydrazinylbenzenesulfonamide hydrochloride (HBSH), was employed as a surface passivator to reduce defects and non-radiative recombination at the perovskite-electron transport layer (ETL) interface. It was demonstrated that the HBSH incorporated through post-treatment induces crystal growth to reduces the GB of the perovskite films and improves their crystallinity. Importantly, it was found that HBSH can suppress charge recombination by passivating defects through coordination or hydrogen bonding with perovskite, as well as inhibit the degradation of perovskite by restraining ion migration. In addition, the energy level matching at the perovskite-ETL interface is enhanced, resulting in improved charge transport capacity and reduced energy losses due to non-radiative recombination. Consequently, the efficiency of the PSCs post-treated with HBSH increased to ∼22 %, while the unencapsulated devices retained more than 95 % of their initial power conversion efficiency for 2760 h in a nitrogen atmosphere and 94 % of their initial efficiency for 2136 h in a 65 °C conditions.