Band gap tuning through cation and halide alloying in mechanochemically synthesized Cs₃(Sb_1−xBi_x)₂Br₉ and Cs₃Sb₂(I_1−xBr_x)₉ solid solutions

Abstract

Modulation of optical properties of lead-free defective perovskites can contribute to design optimized materials for several applications ranging from photodetection to photocatalysis. Here, we explored two novel alloying strategies in...

Band-bowing effects in lead-free double Cs2AgBixSb1−xCl6 perovskites and their anion-exchanged derivatives

“…Considering the single-phase character of CABSC double perovskites, this behavior can be attributed to the band-bowing effect, often observed for solid-solution semiconductors 24,25 including mixed-metal halide perovskite and perovskite-like compounds. 26–30 The band-bowing in perovskites was attributed to local inhomogeneities in the composition and lattice of the alloyed semiconductor compounds. 26,27 Alternatively, the non-linear bandgap behavior was related to an energy mismatch between atomic orbitals of two different metal cations contributing to the band edges.…”

“…29 For the same phase-pure Cs 3 (Bi x Sb 1− x ) 2 Br 9 alloys, but produced via a mechano-chemical treatment of mixtures of Cs 3 Bi 2 Br 9 and Cs 3 Sb 2 Br 9 , the lowest bandgap was observed at x = 0.2–0.3. 30 The ambiguity in the reported position of the lowest bandgap 29,30 can indicate that a combination of different reasons is responsible for the observed band-bowing effects. These reasons can be both of a chemical nature as assumed in ref.…”

Bandgap lowering in mixed alloys of Cs3Bi2−xSbxBr9 perovskite powders

“…At the same time, the XRD pattern of the prepared Cs 3 Bi 2 Br 9 matches well with the standard Cs 3 Bi 2 Br 9 (PDF# 44-0714), and no phase impurities are detected, indicating that the crystals we synthesized are phase-pure. To better demonstrate the successful doping of Sb 3+ , the Rietveld method 1 was used to calculate the lattice parameters, and the result is shown in Table 1. Since Bi 3+ (154.7 pm) and Sb 3+ (145 pm) ions have similar ionic radii and the same crystal structures of the two end elements, modifying the linear trend of the lattice volume in Table 1 meets the requirements of Vegard's law of solid solution, demonstrating the total solubility of Sb/Bi in the lattice.…”

“…In the past decade, the development of metal halide perovskites (MHPs) has driven the vigorous development of photovoltaic devices, 1 light-emitting diodes, semiconductor lasers, and photocatalysts. 2 Since the toxicity of lead has always been a concern for the environment and health and safety, lead-free halide perovskites are of great significance.…”

Mapping Uncharted Lead-Free Halide Perovskites and Related Low-Dimensional Structures

“…Figure 9 shows the three most used methods for the synthesis of these complex compositions: hydrothermal, supersaturation, and the solvent-free solid-state method [96]. Less common ways, but also solvent-free methods, include mechanochemical synthesis [103,104], as well as the melt-based Bridgman technique [105]. The hydrothermal crystal growth of DPs occurs in an aqueous mixture of inorganic salts in a sealed autoclave reactor, for which the system heats up to the reaction temperature and then slowly cools down.…”