Effect of Bidentate Ligand Additive in Tin Perovskite Solar Cells

Tin- perovskite solar cell (Sn-PSC) is limited by their poor stability arising from facile tin oxidation and uncontrolled film growth. Here, we introduced a multifunctional bidentate ligand, formohydrazide (FHZ) as an additive into FASnI3 perovskite film. This additive is found to be effective for the control of Sn-oxidation and forms pin-hole free film morphology. The Sn-PSCs with FHZ additive enhanced the device efficiency from 9.93% (for control Sn-HaP) to 13.14 % (for device with FHZ additive) with higher reproducibility and superior device stability. The device analysis suggests that the hydrazide additive significantly passivates the bulk and surface defect in the Sn-PSCs. This report gives insights into the film growth properties, device photo-physics, and defect analysis correlating with device performance and device stability.