No abstract

Maintaining the stability of tin halide perovskites is a major challenge in developing lead-free perovskite solar cells (PSCs). Adding extra SnX2 (X = F, Cl, or Br) in the precursor solution to inhibit Sn2+ oxidation is an essential strategy to improve device efficiency and stability. However, SnX2 on the surface of perovskite grains tends to prohibit charge transfer across perovskite films. Here, we report a coadditive engineering approach by introducing antioxidant gallic acid (GA) together with SnCl2 to improve the performance of tin-based PSCs. The SnCl2–GA complex can not only protect the perovskite grains but also more effectively conduct electrons across it, leading to highly stable and efficient PSCs. The unencapsulated devices can maintain ∼80% of their initial efficiency after 1000 h of storage in ambient air with a relative humidity of 20%, which is the best air stability achieved in tin-based PSCs to date.

Bi-functional ammonium hypophosphite (AHP) is introduced to improve the performance and long term stability of FASnI3 solar cells.

• Regional spontaneous activity changes were detected in PI patients. • Decreased or increased ReHo of some regions was identified in PI patients. • Significant correlations between mean ReHo and SDS scores were found.

Sn–Pb mixed perovskites with bandgaps in the range of 1.1–1.4 eV are ideal candidates for single‐junction solar cells to approach the Shockley–Queisser limit. However, the efficiency and stability of Sn–Pb mixed‐perovskite solar cells (PSCs) still lag far behind those of Pb‐based counterparts due to the easy oxidation of Sn2+. Here, a reducing agent 4‐hydrazinobenzoic acid is introduced as an additive along with SnF2 to suppress the oxidation of Sn2+. Meanwhile, a vertical Pb/Sn compositional gradient is formed spontaneously after an antisolvent treatment due to different solubility and crystallization kinetics of Sn‐ and Pb‐based perovskites and it can be finely tuned by controlling the antisolvent temperature. Because the band structure of a perovskite is dependent on its composition, graded vertical heterojunctions are constructed in the perovskite films with a compositional gradient, which can enhance photocarrier separation and suppress carrier recombination in the resultant PSCs. Under optimal fabrication conditions, the Sn–Pb mixed PSCs show power conversion efficiency up to 22% along with excellent stability during light soaking.