Putting DFT to trial: For the exploration to correlate structural, electronic and optical properties of M-doped (M = Group I, II, III, XII, XVI) lead free high piezoelectric c-BiAlO₃

Density functional theory is implemented using GGA-PBE functional for the exploration of structural, electronic and optical properties of M-doped BiAlO₃, where M being Cs from Group I, Mg from Group II, Sc from Group III, Zn from Group XII and Se from Group XVI. Equilibrium lattice parameters, DOS, electronic band structures, and optical properties of M-doped BiAlO₃ are computed and compared after inclusion of different dopants. There is excellent agreement of the computed lattice parameters for all dopants with the existing literature. Transition metal substitution transformed indirect band gap (1.487 eV) of pure cubic BiAlO₃ into a direct band gap. Cs doping induced an increment in electronic band up to a value of 2.27 eV. Burstein-Moss effect is attributed to the upsurge in band gaps through Fermi-level shifting. Optical properties such as dielectric constant, absorption, reflectivity, loss function and refractive index are calculated and compared for different dopants. Rare earth metal doping showed startling results with static refractive index of 24.95 (pure = 2.87) and a static dielectric constant of 600 (pure = 8.2). The optical properties of c-BiAlO₃, performed for the first time, suggests that transition metal doping induced a transition in band gap from indirect form to the direct one and proposes excellent optical properties for rare earth doping for future applications in solar cells.