Fabrication of cost-effective lead-free silver bismuth iodide based mesoscopic Rudorffite solar cells

Lead-free Ag-Bi-I Rudorffite materials, specifically AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7, have garnered substantial attention as prospective alternatives to lead halide perovskites in solar cell technology. Rudorffite-based solar cells have conventionally employed a mesoporous structure, integrating unstable and costly hole-transport layers (HTLs) in conjunction with noble metal electrodes. This study presents carbon-based, all-inorganic AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7 Rudorffite solar cells that circumvent the need for HTLs and noble metal electrodes. The absorber layers composed of AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7 materials were synthesized via melt-solidification. Notably, Ag2BiI5 based solar cell achieved PCE of 0.93 % among all the Silver Bismuth Iodide (SBI) devices which is the highest efficiency reported for Ag2BiI5 solar cell to date. The corresponding solar cell parameters include an open-circuit voltage (V-oc) of 0.634 V and a short-circuit current (J(sc)) of 3.63 mA/cm(2). Consequently, our work presents a pathway toward developing Rudorffite solar cells with simplified fabrication methods and reduced cost.