LARP-assisted synthesis of CsBi(3)I(10) perovskite for efficient lead-free solar cells

Bismuth-based perovskites are an important class of materials in the fabrication of lead-free perovskite solar cells. Bi-based Cs(3)Bi(2)I(9) and CsBi(3)I(10) perovskites are getting much attention due to their appropriate bandgap values of 2.05 eV and 1.77 eV, respectively. However, the device optimisation process plays a key role in controlling the film quality and the performance of perovskite solar cells. Hence, a new strategy to improve crystallization as well as the thin film quality is equally important to develop efficient perovskite solar cells. Herein, an attempt was made to prepare the Bi-based Cs(3)Bi(2)I(9) and CsBi(3)I(10) perovskites via the ligand-assisted re-precipitation approach (LARP). The physical, structural, and optical properties were investigated on perovskite films deposited by the solution process for solar cell applications. Cs(3)Bi(2)I(9) and CsBi(3)I(10)-based perovskite-based solar cells were fabricated using the device architecture of ITO/NiO(x)/perovskite layer/PC(61)BM/BCP/Ag. The device fabricated with CsBi(3)I(10) showed the best power conversion efficiency (PCE) of 2.3% with an improved fill factor (FF) of 69%, V(OC) of 0.79 V, and J(SC) of 4.2 mA cm(−2) compared to the Cs(3)Bi(2)I(9)-based device which showed a PCE of 0.7% with a FF of 47%, V(OC) of 0.62 V and J(SC) of 2.4 mA cm(−2).