A comprehensive computational scrutiny of the optoelectronic, thermodynamic, mechanical and structural attributes of Potassium-based K ₃ XI ₆ (X= In, Ga) double perovskites for optoelectronic applications

Lead free perovskites halides have attracted significant attention from the scientific community as these materials are environmental friendly and possess higher optoelectronic performance; however, their structural analysis still requires systematic investigation. The potential for improved stability and efficiency in optoelectronic applications makes potassiumbased halide perovskites noteworthy. Potassium-based halide perovskites offers lower toxicity and are safer option for environmentally friendly technology. In this work, we have assessed in detail the physical attributes of K 3 XI 6 (X= In, Ga). For analyzing the electron-ion exchange correlation effects, the modified Becke Johnsons (mBJ) is used. To check the stability of these halides, several parameters are computed. The second order stress-strain energy equations are employed for the computation of elastic constants of K 3 XI 6 (X= In, Ga). The mechanical stability is checked via Born’s stability criteria. Sound velocities for K 3 XI 6 (X= In, Ga) along three crystallographic planes [100], [110] and [111] are also analyzed. Direct bandgaps of 2.12 eV and 1.72 eV are attained for K3InI6 are K3GaI6 as revealed via their electronic properties. Both materials reports large optical conductivity and polarization in the visible and UV region and computed bandgaps highlight their applicability for advanced optoelectronic technological applications. Thus overall findings demonstrate that K 3 XI 6 (X = In, Ga) materials are excellent contenders for low-toxicity and energy related applications.