Structure modulation for bandgap engineered vacancy-ordered Cs₃Bi₂Br₉ perovskite structures through copper alloying

Abstract

Lead-free, vacancy-ordered, Cs3Bi2Br9 perovskite is considered a promising inorganic, stable, and non-toxic halide perovskite for optoelectronic and photovoltaic applications. However, its wide bandgap limits its state-of-art. We notice an observable...

A Lead-Free 0D/2D Cs3Bi2Br9/Bi2WO6 S-Scheme Heterojunction for Efficient Photoreduction of CO2

“…The lead-free bismuth halide perovskite semiconductor, as a typical photocatalytic material, has sparked heated discussions in this field, owing to the quantum dot size effects, innocuity, adjustable bandgap, high photoluminescence quantum yield, and competing photoelectrical properties. − The conduction band position of halide perovskite is more negative in comparison with traditional catalysts, indicating that it has a strong reduction ability for the CRR . The all-inorganic cesium bismuth halide (Cs 3 Bi 2 X 9 , X = Cl/Br/I) perovskite PQDS have been widely used for CO 2 reduction.…”

Critical Roles of Octahedron Bilayer Surface/Interior Bromide Defects in Photodynamics of Multi-Quantum-Well-Structured Cesium Bismuth Bromide

“…The broadband luminescence of the Cs 3 Sb 2 Cl 9 film was suggested to arise from some defects . The Br-related defect was proposed as a probable carrier trap in Cs 3 Bi 2 Br 9 . ,,,, However, a comprehensive theoretical study of the point defects in Cs 3 Bi 2 Br 9 and their roles in the radiative and non-radiative recombination processes is still lacking. Here, we use the density functional theory (DFT) calculation to theoretically investigate the intrinsic point defects and their roles in the photodynamics of Cs 3 Bi 2 Br 9 based on the Shockley–Read–Hall (SRH) statistics and multiphonon recombination theory. , Our GW plus Bethe–Salpeter equation ( GW –BSE) calculation reveals a prominent exciton absorption peak, which agrees with the experimentally observed sharp and strong absorption peak and clarifies the debate about its origin. − The calculation shows that the most energetically favorable point defects in Cs 3 Bi 2 Br 9 possess deep thermodynamic transition levels.…”

“…There is a heated debate about the origin of the experimentally observed first sharp absorption peak at around 2.56–2.70 eV in Cs 3 Bi 2 Br 9 . Some supposed that it is assigned to the band edge absorption, ,, and others supposed that it belongs to the exciton absorption. , To theoretically study the origin of this prominent absorption peak, we calculate the imaginary dielectric constant using the GW –BSE method including the electron–hole interaction and using the GW plus independent particle approximation (IPA) method without considering the electron–hole interaction; the spin–orbit coupling (SOC) effect was taken into account in both calculations. The calculated results are compared to the measured ultraviolet–visible (UV–vis) absorption spectrum, as shown in Figure b.…”

“…The lead-free bismuth halide perovskite derivatives have stable crystal structures and promising applications in photocatalysis , and X-ray/γ-ray detection as a result of their large atomic number, high resistivity, and low charge-trap concentration . Among them, Cs 3 Bi 2 Br 9 , a periodic quantum-well-structured semiconductor with a large bandgap, has attracted great interest. , The polaron was sometimes supposed to be responsible for the high performance of the LHP-based photovoltaic devices, , and some researchers believed that the polarons may also form in Cs 3 Bi 2 Br 9 . , Others supposed that the intrinsic point defects might play critical roles in the carrier trapping in Cs 3 Bi 2 Br 9 . ,, The point defects in semiconductors can accommodate defect states in the forbidden gap and sometimes cause non-radiative carrier capture or act as color centers . They could also affect the carrier transport properties of the semiconductor devices and even lead to their degradation. , Some point defects in the LHPs were found to mediate the non-radiative recombination. − There has been a report on the deep defects in the Cs 3 Bi 2 I 9 crystallites .…”

“…12,13 Others supposed that the intrinsic point defects might play critical roles in the carrier trapping in Cs 3 Bi 2 Br 9 . 9,14,15 The point defects in semiconductors can accommodate defect states in the forbidden gap and sometimes cause non-radiative carrier capture or act as color centers. 16 They could also affect the carrier transport properties of the semiconductor devices and even lead to their degradation.…”