Reinforced SnO2 tensile‐strength and “buffer‐spring” interfaces for efficient inorganic perovskite solar cells

Abstract Suppressing nonradiative recombination and releasing residual strain are prerequisites to improving the efficiency and stability of perovskite solar cells (PSCs). Here, long‐chain polyacrylic acid (PAA) is used to reinforce SnO 2 film and passivate SnO 2 defects, forming a structure similar to “reinforced concrete” with high tensile strength and fewer microcracks. Simultaneously, PAA is also introduced to the SnO 2 /perovskite interface as a “buffer spring” to release residual strain, which also acts as a “dual‐side passivation interlayer” to passivate the oxygen vacancies of SnO 2 and Pb dangling bonds in halide perovskites. As a result, the best inorganic CsPbBr 3 PSC achieves a champion power conversion efficiency of 10.83% with an ultrahigh open‐circuit voltage of 1.674 V. The unencapsulated PSC shows excellent stability under 80% relative humidity and 80°C over 120 days.