Thermodynamic and dynamic stability in a new potential CsAgAsCl perovskite: insight from DFT study

In the present study, we propose a novel type of lead-free double halide perovskite Cs 2 AgAsCl 6 material exhibiting exceptional photovoltaic and photocatalytic properties. Density functional theory (DFT) is employed to investigate the photovoltaic and photocatalytic properties based on several significant properties of the Cs 2 AgAsCl 6 material. The thermodynamic stability of Cs 2 AgAsCl 6 has been confirmed by the enthalpy formation, which is −32.36 eV f.u. −1 Dispersion of phonons near the gamma point confirmed the existence of dynamical stability. The constant value of the heat capacity is 59.45 cal per cell K, which is calculated by the Dulong-Petit limit. The GGA-PBE and HSE-06 functional approaches determined indirect bandgaps of 1.31 and 2.49 eV, respectively, for a semiconductor whose electronic properties revealed photocatalytic efficiency. The effective masses of an electron and a hole are 0.46 m e and 0.61 m e , respectively, which may enhance the photocatalytic dye degradation owing to their low carrier effective mass. Notably, better photocatalytic properties, i.e. , dye degradation, are confirmed by the redox potential. The estimated edge potentials of the conduction band (CB) and valence band (VB) are −0.048 and 2.448 eV, respectively, which are greater than the H + /H 2 and O 2 /H 2 O potentials. The Cs 2 AgAsCl 6 material reveals an outstanding optical property that is suitable for photovoltaic applications. Therefore, Cs 2 AgAsCl 6 can act as a potential candidate in the field of photovoltaic and photocatalytic applications. A schematic diagram of the possible energy band level for photocatalytic activity: (a) favorable energy band level, (b) unfavorable VBM, and (c) unfavorable CBM position.