Sb‐Substituted Cs₂AgBiBr₆—As Much As It Could Be?—Influence of Synthesis Methods on Sb‐Substitution Level in Cs₂AgBiBr₆

Abstract

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

Sb-Substituted Cs2AgBiBr6/g-C3N4 Composite for Photocatalytic C(sp3)–H Bond Activation in Toluene

“…51 Nevertheless, due to the high formation energy of Cs 2 AgSbBr 6 and considering the small ionic radius of Sb 3+ relative to Bi 3+ , synthesizing Cs 2 AgBiBr 6 powdered samples with a high level of Sb substitution is a challenging task. 47,52 In a single photocatalyst, rapid charge recombination is dominant because of the extraordinarily strong coulombic force between photogenerated electrons and holes, leading to low photoactivity. This issue can be addressed by coupling the material with another semiconductor to form a heterostructure, in which the charge carriers can be efficiently separated due to the band bending and the formation of an internal electric field.…”

“…Sb incorporation leads to an asymmetric charge distribution that decreases the adsorption energy for methylbenzene and attracts benzylic hydrogen, efficiently reducing the C–H bond activation barrier, thus enhancing the photocatalytic methylbenzene conversion . Nevertheless, due to the high formation energy of Cs 2 AgSbBr 6 and considering the small ionic radius of Sb 3+ relative to Bi 3+ , synthesizing Cs 2 AgBiBr 6 powdered samples with a high level of Sb substitution is a challenging task. , …”

In Situ Crystallization of the Inorganic Lead-Free Halide Double Perovskite Cs2AgBiBr6 via Spray-Drying

“…Although there are no serious toxicity concerns about the CABB precursors themselves, holding a mixture of concentrated HBr near its boiling point for several hours is quite delicate and poses severe dangers. Moreover, HBr as a solvent is limited as soon as the electronic properties, such as the bandgap energy, are tentatively varied by cationic substitution, for instance, by Sb 3+ substitution for Bi 3+ . These safety concerns even increase once large amounts of CABB absorber powders are required and the batch size is increased.…”

Elucidating the Factors Limiting the Photovoltaic Performance of Mixed Sb–Bi Halide Elpasolite Absorbers

“…[14] Smaller bandgaps have been reported in bulk powders and single crystals, with values as low as 1.55 eV reported. [27,28] Preliminary attempts have been made to investigate whether these reductions in bandgap could be translated into improvements in PV performance. However, groups have thus far reported that Sb alloying leads to a reduction in the PCE from >1% for Cs 2 AgBiBr 6 down to <0.3% for alloyed Sb-Bi elpasolite absorbers.…”