Efficient inverted CsPbI3 perovskite solar cells fabricated in common air

A humidity-assisted polymerization strategy is proposed to fabricate efficient CsPbI3 PSCs in common air regardless of humidity, through introducing MMDS additive. MMDS will react with and consume water in moisture air, then self-polymerize into water-resisting polymer, blocking further water penetration during film fabrication. Resulting PSCs exhibit high efficiency of over 18% (highest of 19%) even under 80% humidity. [Display omitted] •Fabricating efficient CsPbI3 perovskite solar cells by polymerization strategy.•MMDS reacts with and consumes water in moisture air, then self-polymerize.•The devices exhibit high efficiency of over 18% even under 80% humidity.•The devices retain 88% of initial efficiency after MPP tracking for 1000 h. 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.