Impact of cesium on the phase and device stability of triple cation Pb–Sn double halide perovskite films and solar cells

Abstract

Csx(MA0.17FA0.83)1−xPb1−ySny(I0.83Br0.17)3 perovskites with cubic-phase morphologies were deployed in solar cells, achieving high efficiencies and improved stability for high Sn-containing devices.

Tin Halide Perovskite (ASnX3) Solar Cells: A Comprehensive Guide toward the Highest Power Conversion Efficiency

“…If we consider Cs + , that is the nonradioactive element with the largest ionic radius, the tolerance is comprised between 0.85 and 0.88, as shown in Table 1 for every combination of B and X. For this reason, CsBX 3 perovskites are not stable in the cubic black‐phase (bandgap 1.73 eV) at ambient temperature and tend to transform into orthorhombic perovskite characterized by the yellow color and a larger bandgap (>3 eV) . For this reason, Cs is usually substituted by MA and FA that lead to optimal tolerance factor values (see Table ).…”

A Thermodynamically Favored Crystal Orientation in Mixed Formamidinium/Methylammonium Perovskite for Efficient Solar Cells

“…For the FAPbI 3 perovskite film, the diffraction intensity along (001) direction was substantially increased in most case, as a result of its cubic phase. With respect to MA/FA mixed perovskites, a preferred orientation along (100) and excellent crystallinity were obtained through Sn doping, Br doping, or the templating effect associated to the specific beneath layer . Besides, a preferred orientation along (021) or (012) in mixed FA/MA perovskite film could be achieved by altering organic cation concentration, or meniscus‐assisted solution printing strategy .…”

Tuning cesium–guanidinium in formamidinium tin triiodide perovskites with an ethylenediammonium additive for efficient and stable lead-free perovskite solar cells

“…In our previous work, we showed that the band gap of Cs x (MA 0.17 FA 0.83 ) 1Àx Sn(I 0.83 Br 0.17 ) 3 perovskites decreases with decreasing lattice parameter due to a smaller average cation radius. 33 Both A-site induced BX 6 octahedral tilting and B-X overlap on the conduction and valence band edges of perovskites influence these band gap trends. 34 The correlation between the band gap decrease and the lattice parameter decrease for (CsGA) x without EDAI 2 reflects that the same mechanism is occurring, where the increased isotropic lattice constrictions and B-X overlap make the valence band maximum shift upwards more than the conduction band minimum.…”