Investigation of the Double Perovskite Halides Cs2CuSbH6 (H = Cl, Br, I): Electronic and Optical Properties for Flexible Electronics Device Applications

Double perovskite halides (DPHs), specifically Cs₂CuSbH₆ (where H = Cl, Br, and I), serve as key components in the fabrication of flexible electronic devices, including solar cells, wearable biodevices, and optoelectronics. Utilizing QuantumATK NanoLab Software Tool, an investigation into the mechanical, electrical, optical, and structural properties of these halide perovskites was undertaken. Structural stability was validated by optimizing the structure and tolerance factors of these compounds, demonstrating positive values of C₁₁, C₁₂, and C₄₄. These double perovskite halides (DPHs) align with the Born–Huang stability criterion following the trend C₁₁ > C₁₂ > C₄₄. Electronic characteristics were determined by assessing band structures, density of states (DOS), and projected density of states (PDOS). The investigated Cs₂CuSbCl₆, Cs₂CuSbBr₆, and Cs₂CuSbI₆ compounds exhibited indirect band gaps of 0.95, 0.60, and 0.20 eV, respectively, indicative of their semiconducting nature. In our research, the optical properties, including dielectric functions, refractive indices, reflectivity, extinction losses, and absorption coefficients, have been computed. Calculations revealed static dielectric function values Re(ε) for Cs₂CuSbCl₆, Cs₂CuSbBr₆, and Cs₂CuSbI₆ as 3.716, 4.6033, and 6.133, respectively. Notably, absorption bands for these materials were identified within the visible range spanning wavelengths from 378 to 632 nm, 356 to 688 nm, and 373 to 720 nm for Cl, Br, and I, respectively. Furthermore, the refractive indices of Cs₂CuSbCl₆, Cs₂CuSbBr₆, and Cs₂CuSbI₆ demonstrated values below 2.0 for higher energy spectra, elucidating the propagation of light within these materials. In conclusion, the findings suggest promising applications for DPHs, specifically Cs₂CuSbH₆ (H = Cl, Br, and I), in future solar cells, optoelectronic devices, and various other flexible electronic applications.