Fabrication of lead-free CsBi3I10 based compact perovskite thin films by employing solvent engineering and anti-solvent treatment techniques: an efficient photo-conversion efficiency up to 740 nm

Abstract

Bismuth based perovskites are emerging as a candidate for photovoltaic applications due to their low-toxicity, high structural stability, and suitable applications in photovoltaic applications. Here in this work, bismuth halide perovskite films with the stoichiometric composition of ABi₃I₁₀ (A = Cs, FA and MA) are synthesized by a one step solution process. By optimizing the appropriate anti-solvent dripping techniques, the surface morphology and optical properties of these perovskite thin films have been improved. Among the synthesized materials, CsBi₃I₁₀ perovskite showed extended absorption up to 700 nm and the bandgap was reduced to 1.75 eV. An inverted planar perovskite solar cell (PSC) employing the CsBi₃I₁₀ as an absorber layer was fabricated which showed a maximum power conversion efficiency of 0.63%. In addition, the fabricated PSC exhibited a red-shifted incident photon to current conversion efficiency (IPCE) up to 740 nm, which is higher than those of the existing bismuth-based PSCs. This improvement in the IPCE shows the potential of CsBi₃I₁₀ as an absorber for Pb-free PSCs.