First-principles investigation of structural, electronic, elastic, and thermoelectric properties of cubic XPbI <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si152.svg" display="inline" id="d1e3496"> <mml:msub> <mml:mrow/> <mml:mrow

The hybrid perovskites are attracting a lot of attention in this category regarding the possibilities to tune their physical properties and their future implementation across energy applications. Nominal worthy lead perovskite is another material that is promising as a solar cell and thermoelectric device. Yet, the relation of properties of structure in the cation-substituted lead iodide perovskites remains to be well comprehended, in particular mechanical stability and thermoelectrical conductivity. In this case, we present a systematic analysis of NH 4 PbI 3 , PH 4 PbI 3 , AsH 4 PbI 3 , and SbH 4 PbI 3 , composed of the first-principles density functional theory by Quantum ESPRESSO. Structural, electronic, mechanical, thermal, and transport properties were determined using the PBE-GGA functional and BoltzTraP code. All these can be found in the form of a stable cubic crystal structure with a lattice constant that lies in the range of 6.365 to 6.461 Å. The values of the direct band gaps lie between 1.42 and 1.60 eV, which can be taken as proof of good visible-light absorbers. The elastic constants confirm that they are born stable, with bulk moduli that fall in the range of 23.07 to 25.43 GPa. These compounds have high heat storage at moderate temperatures of about 295 °C, and the heat capacity displays Debye-like characteristics up to approximately 125 J, mol −1 , K −1 . A power factor of 8.60 W/mK 2 and a ZT of around 1 result in the highest Seebeck coefficient of 2813 μ V/K at 300 K, suggesting the optimal doping to exploit. The interesting fact that n-type material always performs better than p-type material at a given temperature is a great incentive for advancing other doping methods. The results exceed much of the earlier thermoelectric materials and demonstrate potential in the conversion of waste heat into renewable resources. Future research should concentrate on the stability of experimental synthesis, bulk fabrication, and further examination.