Halide Double Perovskites Cs₂PdBr_6–xI_x with Tunable Bandgaps for Solar Cells

Abstract

Inorganic lead-free vacancy-ordered double perovskites with the chemical formula A2BX6 are promising candidates to overcome Pb-based organic–inorganic perovskite’s toxicity and instability issues. We designed the mixed-halide double perovskites Cs2PdBr6–x I x by halogen anions substitution. The structure, stability, and electronic and photoelectric properties were explored using density functional theory (DFT). The negative value of the formation energy indicated that the Cs2PdBr6–x I x perovskites are thermodynamically stable. These perovskites exhibit tunable bandgap values in the range of 0.77–1.73 eV, which are direct or quasi-direct bandgaps except for Cs2PdBr3I3. Their absorption spectrum shows that the absorption range of visible light expands significantly. The theoretical spectral limit maximum efficiency (SLME) of Cs2PdBr5I with 1.3 eV and Cs2PdBr4I2 with 1.04 eV reached 32 and 30.4%, respectively, which are becoming comparable to or slightly surpassing CH3NH3PbI3, indicating they could be candidates for single-junction solar cells. In addition, the Cs2PdBr3I3 and the Cs2PdBr4I2, with the bandgap of 1.12 and 1.04 eV, respectively, could be the bottom cell to form the homogeneous tandem solar cells with the Cs2PdBr6, which could be the top cell with the bandgap of 1.73 eV.

Recent Advances in Carbon Nanotube Utilization in Perovskite Solar Cells: A Review

“…Improvements in the perovskite film quality have resulted from extensive efforts to optimize the manufacturing processes, fine tune the band gap, and passivate flaws. The Schottky-Queisser limit predicts that photovoltaic solar cells including a perovskite material with an appropriate band gap could achieve power conversion efficiencies greater than 30% [91]. Changing the perovskite's chemical makeup might do this.…”

Structural Properties of Some Vacancy-Ordered Platinum Halide Perovskites

“…The band gap of these halides can be tuned by substitution of either the A-site cation or the halide anion. 10 Understanding the thermal stability of platinum halides will enable a more informed and strategic approach to catalyst synthesis.…”

“…The vacancy-ordered double perovskites A 2 PtCl 6 and their complex salts find use in technologically important materials spanning applications in photovoltaics, catalysis, and industrial metallurgy processes. The band gap of these halides can be tuned by substitution of either the A -site cation or the halide anion . Understanding the thermal stability of platinum halides will enable a more informed and strategic approach to catalyst synthesis.…”

“…Despite the impressive performance of perovskite-based solar cells, their instability to moisture and/or oxygen and the toxicity of lead precludes their widescale commercial utilization driving the search for new materials. Vacancy-ordered double perovskites have emerged as a flexible scaffold that enables the lead to be replaced with an environmentally benign metal while retaining the compositional and structural flexibility of the perovskite structure that can be exploited to optimize the desirable properties. , The vacancy-ordered double perovskite structure has the general formula A 2 BX 6 and is derived from the archetypal perovskite structure by doubling the ABX 3 unit cell along all three crystallographic axes and then removing every second B -site cation, as illustrated schematically in Figure . The structure can also be described as an antifluorite arrangement of A -site cations and anionic [ BX 6 ] units.…”