Efficient inverted CsPbI₃ perovskite solar cells fabricated in common air

CsPbI₃ perovskite shows great potential for photovoltaic applications due to its excellent photovoltaic performance and thermal stability. However, CsPbI₃ perovskite solar cells (PSCs) are extremely sensitive to moisture, and strict humidity control is necessary during its fabrication, limiting their further commercialization. Here, we report the fabrication of efficient CsPbI₃ PSCs in common air without humidity control through introducing humidity-assisted polymerizable additive of mercaptopropylme-methyldimethoxysilane (MMDS). During CsPbI₃ film formation, MMDS molecules can rapidly react with water in humidity air, and then self-polymerize to a water-resistant polymer at grain boundaries to reduce further moisture invasion. Moreover, -SH group in MMDS can passivate under-coordinated Pb²⁺ and reduce the trap density in CsPbI₃ films. As a result, high efficiency of > 18 % is realized in inverted CsPbI₃ PSCs regardless of relative humidity among 40 ∼ 80 %. And the best efficiency reaches 19 %, which is among the highest efficiency of CsPbI₃ PSCs in inverted configuration. In addition, stability of MMDS-CsPbI₃ PSCs is also greatly improved and 88 % of initial efficiency can be retained after MPP tracking for 1000 h.