Multidentate Coordination Induced Crystal Growth Regulation and Trap Passivation Enables over 24% Efficiency in Perovskite Solar Cells

Crystal growth regulation has become an effective solution to reduce the defects at grain boundaries (GBs) and surfaces of perovskite films for better photovoltaic performances. Oxime acid materials are maturely used as selective collectors in the flotation separation of oxide minerals. Such materials, showing a strong coordination effect and high selectivity with lead, may have great potential in controlling the crystal growth and passivating the defect of perovskite film, which are rarely applied in perovskite solar cells (PerSCs). Herein, an oxime acid-based material with multi-coordination sites, ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate (EHA), is incorporated into the PbI2 precursor solution to fabricate high-performance PerSCs using a two-step method. The multidentate coordination effect of EHA can link and integrate the PbI2 colloidal clusters to achieve pre-aggregation in the PbI2 precursor solution, facilitating the sequent crystal growth progress of perovskite film. Meanwhile, EHA can connect grains and fill GBs, which is favorable for charge transfer and passivating both Pb-I anti-site and iodine vacancy defects. As a result, the optimal devices show an enhanced efficiency of 24.1% and excellent humidity and thermal stability. This work affords a promising strategy to fabricate efficient and stable PerSCs via multidentate coordination-induced crystallization control and GB passivation.

Automated summary

This study demonstrates the use of oxime acid-based materials with multi-coordination sites to control the crystal growth and passivate grain boundary defects in perovskite films, leading to the fabrication of high-performance perovskite solar cells. The optimal devices exhibit enhanced efficiency and excellent humidity and thermal stability.