Exploring Tl 1-xB x as: A New Addition to the Family of Advanced Materials with Distinct Structural, Electronic and optical Properties

In this study, we present a theoretical investigation of the structural, electronic, and optical properties of the ternary compound Tl₁₋ₓBₓAs (0 < x < 1) crystallizing in the zinc blende (ZB) structure, using density functional theory (DFT) within both the generalized gradient approximation (GGA) and the modified Becke–Johnson (mBJ-GGA) potential. The calculated results reveal that the crystal lattice maintains its structural stability across all studied boron concentrations. Within the GGA approach, the alloy exhibits a metallic nature with no distinct band gap between the valence and conduction bands. However, when the mBJ-GGA correction is applied a remarkable direct band gap emerges at the boron concentration of x = 0.75, highlighting its semiconducting behavior. From an optical point of view the imaginary part of the dielectric function indicates that the absorption edge starts from zero energy for low boron concentrations (x = 0.25 and 0.5) and extends up to around 8 eV while it shifts to approximately 10 eV for x = 0.75, indicating a wider absorption range. This broad optical response combined with structural stability and tunable electronic properties suggests that Tl₁₋ₓBₓAs alloys are promising materials for advanced technological applications particularly in optoelectronic and semiconductor–metal transition devices.