A Halide‐Based Perovskite CsGeX3 (X = Cl, Br, and I) for Optoelectronic and Piezoelectric Applications

By means of the study of the first principles within the framework of density functional theory, the inorganic metal halide perovskite CsGeX3 (X = Cl, Br, and I) is thoroughly investigated for its potential application in the field of green energy harvest. The structural, electronic, optical, mechanical, and piezoelectric properties have been calculated. Herein, the computed electronic properties reveal a direct bandgap semiconducting nature with electronic bandgap Eg$_{\text{g}}$ = 2.01, 1.38, and 0.85 eV for X = Cl, Br, and I, respectively. Since the most prominent absorption peak falls within the vis–UV region, this implies that they are the potential candidates for photovoltaic applications. To check and verify the thermal stability, the MD simulation was performed with time steps up to 5 ps. The highest piezoelectric coefficient values are 0.731, 1.829, and 12.48 C m−2 for X = Cl, Br, and I, respectively. The higher piezoelectric responses indicate the signature of the efficient energy materials for energy harvest through electromechanical processes. Properties of Pb‐free halide perovskites CsGeX3 (X = Cl, Br, and I) are investigated using density functional theory (DFT) simulations. DFT‐1/2 generalized gradient approximation (GGA)‐1/2, and meta‐GGA have been employed in the electronic properties for precise outcomes. Stabilities of the studied compounds have been proved by satisfying the Born stability criteria by their elastic constants. Thermal effect stabilities have been proved using molecular dynamic simulation. The studied Cs‐based halide perovskites have great potential for optoelectronics and piezoelectric applications.