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

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.