Zr-metal–organic framework based cross-layer-connection additive for stable halide perovskite solar cells

The poor stability of metal halide perovskite seriously affects the large-scale commercial application of perovskite solar cells (PSCs). Here, a large-particle Zr-based metal–organic framework (Zr-MOF), e.g. UiO-66 (NH2), is added to the precursor solution of SnO2 electron transport layer (ETL), realizing a cross-layer modification of (1) ETL, (2) perovskite active layer and (3) theirs interface simultaneously. We find that the SnO2 particles are dispersed into the ordered porous scaffold of Zr-MOF, to form an ETL with improved crystallinity, reduced defect states and increased contact area with active perovskite film. For the subsequently deposited perovskite layer, the crystallization along the vertical direction is significantly optimized, and the defects are passivated by the bottom-up infiltrated Zr-MOF, so as to suppress the ion migration process. The power conversion efficiency (PCE) of one-step fabricated Zr-MOF-modified MAPbI3 based PSCs is optimized from 17.48% to 18.25%, and remaining 99% of its initial value after storage for 800 h under ambient conditions with the relative humidity over 60%. This work provides a simple cross-layer passivation strategy to improve the performance and stability of PSCs using highly designable MOF materials.