Green-Solvent-Processed Lead-free Perovskite Solar Cells

Tin-based perovskite has been considered as one of the most potential candidates for the lead-based perovskite. The solution proceed method were widely utilized in fabricating tin perovskite solar cells. So far, all fabrication process for tin perovskite solar cells involved the toxic organic solvents, which is contrary to the development of environmentally friendly perovskite solar cells. In this study, we report for the first time, by using a mixed green solvent N-diethyl formamide and green 1,3-Dimethyl-3,4,5,6-Tetrahydro-2 (1H)-pyrimidinone as precursor solvent, and a green solvent dibutyl ether as antisolvent, a high-quality FA0.75MA0.25SnI3 film was achieved. The optical band gap of the prepared perovskite layer was 1.36 eV, which was close to the ideal band gap. The green-solution-proceed perovskite films showed reduced defect density. As a consequence, the champion green-solution-proceed photovoltaic device achieved a power conversion efficiency of 4.4%. Moreover, it still maintains 80% of the initial efficiency after 600 hours storage in a nitrogen atmosphere. This work would promote the perovskite solar cells from a “new” technique to the “new and green” technique.