Lead-free halide perovskite solar cells with high photocurrents realized through vacancy modulation

A study was conducted to demonstrate that high photocurrent densities of more than 22 mAcm-2 can be attained by utilizing CsSnI 3 as an absorber in solid state perovskite solar cells. Photovoltaic devices with the configuration FTO/compact TiO2 / mesoporous TiO2 /CsSnI3/HTM/Au were prepared. CsSnI3 layers were spin coated on to -300 nm thick mesoporous layers. Two HTMs ? 4, 4', 4''-tris (N,N-phenyl-3-methylamino) triphenylamine (m-MTDATA) and Spiro-OMeTAD were employed for this study. Using DMF and 2-methoxyethanol as solvents for the CsSnI3 resulted in the formation of large islands on the TiO2 scaffold, with significant areas of exposed TiO2.Pristine CsSnI3 as the light absorber does not result in a functional photovoltaic device while compositions with added SnF2, display photovoltaic effect. The unprecedented short circuit photocurrents observed from a pure Sn-based perovskite system reflect the enhanced light harvesting in the infrared region of the solar spectrum.