Investigation of mechanical, optoelectronic, and thermoelectric properties of double perovksites Li2CuBiZ6 (Z = Cl, Br, I) for solar cell applications.

• Theoretically examined the physical features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). • Elastic properties are investigated for structural stability. • Electronic and optical properties for solar applications. • The dispersion of light is explained by ε 1 (ω). • Due to its higher Seebeck coefficient, Li 2 CuBiCl 6 possessed a larger power factor than Li 2 CuBiBr 6 and Li 2 CuBiI 6. Due to their potential applications for optoelectronic and thermoelectric devices, Li-based double perovskites (DPs) have been widely investigated. In current article, we theoretically examined the mechanical, optoelectronic and thermoelectric features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). We employ the generalized gradient approximation (PBEsol) for examining the structural and elastic characteristics of these compounds, while the modified Becke-Johnson (mBJ) functional is used for obtaining an improved accord of the thermoelectric and electronic characteristics with experimental observations. For the stability of all DPs, the Born Criteria and formation energy are investigated. The cubic symmetry's elastic constants are examined to determine the difference between ductile and brittle nature, anisotropy, and Debye temperatures. The bandgaps are 2.0 eV, 1.7 eV, and 1.3 eV, for Li 2 CuBiCl 6 , Li 2 CuBiBr 6, and Li 2 CuBiI 6 , respectively, as determined by the mBJ potential. All DPs were also examined regarding optical absorption, refractive index, and dielectric constants for the energy range 0–10 eV, ensuring the absorption among visible regions. Furthermore, all DPs are appropriate candidates for thermoelectric applications due to the lower lattice thermal, higher Seebeck coefficient, thermal conductivity, and Figure of merit (ZT), which are all elucidated by Boltzmann classical theory. [ABSTRACT FROM AUTHOR]