silicon solar cell. [3][4][5][6] Pb-based halide perovskites have shown remarkable and unique PV properties compared to silicon such as tunable bandgaps, high optical absorption coefficients, balanced effective masses of electrons and holes, longer diffusion lengths, extended lifetimes of the photogenerated charge carriers, and smaller exciton binding energies. [7][8][9] Facile fabrication technology with high defect tolerance is another advantage in Pb-based halide perovskites. However, a major problem to be solved is the toxicity of the element lead (Pb) in halide perovskites, let alone moisture and air sensitivities. The toxicity issue should be solved by finding new alternative materials for substituting Pb, and one of the alternatives can be Bi 3þ -or Sb 3þ -based perovskites. Several combinations of elements together with Bi 3þ or Sb 3þ ions are proposed to be possible based on the theoretical calculations, but only a few materials have been experimentally synthesized. [10] In the case of Bi 3þ , the research focus has been devoted to Cs 2 AgBiBr 6 due to its high stability and nontoxicity. [11] Especially Cs 2 AgBiBr 6 was theoretically and experimentally tested to be a potential candidate for photovoltaic application due to its long charge carrier lifetime compared to the other potential Pbfree perovskites. [12][13][14][15][16][17] Some of the highest power conversion efficiencies (PCEs) are reported to be 2.84% [18] and 3.11%. [19] Compared to Pb-based halide perovskites, the indirect bandgap

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adpr.202200061.