Exploring the properties of quaternary X2NaTlF6 (X = Cs, Rb) halide double perovskite materials for energy conversion, harvesting, and storage using density functional theory

• Published in: Optical and quantum electronics Vol. 56; no. 1
• Main Authors: Ayub, Gohar, Husain, Mudasser, Sfina, Nourreddine, Khan, Rajwali, Sohail, Mohammad, Waheed, Hafiza Sumaira, Elhadi, Muawya, Abdullaeva, Barno Sayfutdinovna, Rahman, Nasir
• Format: Journal Article
• Language: English
• Published: New York Springer US 2024; Springer Nature B.V
• Subjects: Cesium; Characterization and Evaluation of Materials; Computer Communication Networks; Density functional theory; Elastic anisotropy; Elastic properties; Electrical Engineering; Energy conversion; Energy harvesting; Free energy; Heat of formation; Lasers; Mathematical analysis; Modulus of elasticity; Optical Devices; Optical properties; Optics; Optoelectronic devices; Perovskites; Photonics; Physics; Physics and Astronomy; Refractivity; And mechanical properties; DFT; Optoelectronic properties; Halide double perovskites; WIEN2K; Structural properties
• ISSN: 0306-8919; 1572-817X
• DOI: 10.1007/s11082-023-05669-w

Double perovskites (DPs) have attracted considerable attention for their potential in optoelectronic and thermoelectric applications. In this study, we utilize the WIEN2K code, which relies on density functional theory, to analyze the structural, electronic, mechanical, and optical properties of X
2
NaTlF
6
(X = Cs, Rb). To assess the material’s structural durability, we determine the tolerance factor, and thermodynamic stability is examined through formation energy and phonon calculations. Mechanical stability is confirmed through the relationship between elastic constants, specifically C
11
- C
12
 > 0, C
11
 > 0, C
11
 + 2C
12
 > 0, and B > 0. Furthermore, an analysis of elasticity using the IRelast package reveals their resilience, anisotropic properties, and mechanical stability. The calculated elastic moduli indicate that Rb
2
NaTlF
6
displays ductile behavior, while Cs
2
NaTlF
6
demonstrates brittleness, depending on the specific elastic constant under consideration. Utilizing the modified Beck and Johnson potential (TB-mBJ), we determine band gaps of 1.23 eV for Rb
2
NaTlF
6
and 1.64 eV for Cs
2
NaTlF
6
DPs. Additionally, we investigate optical properties, including refractive index, dielectric constant, and reflectivity, providing further insights into their behavior. Optical property calculations for both compounds suggest their potential suitability for use in optoelectronic devices, particularly LEDs, owing to their UV-Vis range absorption characteristics.