A Bifunctional Carbazide Additive For Durable CsSnI3 Perovskite Solar Cells

Abstract

AbstractInorganic CsSnI3 with low toxicity and a narrow bandgap is a promising photovoltaic material. However, the performance of CsSnI3 perovskite solar cells (PSCs) is much lower than that of Pb‐based and hybrid Sn‐based (e.g., CsPbX3 and CH(NH2)2SnX3) PSCs, which may be attributed to its poor film‐forming property and the deep traps induced by Sn4+. Here, a bifunctional additive carbazide (CBZ) is adapted to deposit a pinhole‐free film and remove the deep traps via two‐step annealing. The lone electrons of the NH2 and CO units in CBZ can coordinate with Sn2+ to form a dense film with large grains during the phase transition at 80 °C. The decomposition of CBZ can reduce Sn4+ to Sn2+ during annealing at 150 °C to remove the deep traps. Compared with the control device (4.12%), the maximum efficiency of the CsSnI3:CBZ PSC reaches 11.21%, which is the highest efficiency of CsSnI3 PSC reported to date. A certified efficiency of 10.90% is obtained by an independent photovoltaic testing laboratory. In addition, the unsealed CsSnI3:CBZ devices maintain initial efficiencies of ≈100%, 90%, and 80% under an inert atmosphere (60 days), standard maximum power point tracking (650 h at 65 °C), and ambient air (100 h), respectively.