First-principles Study On Inorganic Perovskites And Two-dimensional Optical Materials

Inorganic perovskites and two-dimensional optical materials have great potential optoelectronic applications in semiconductor materials and solar cells for the good electronic structures and optical properties.In this work,we systematically study and calculate the crystal structure,electronic properties,light absorption properties and photocatalytic properties of the inorganic perovskite structure of RbSnX3(X=Cl,Br,I)and the two-dimensional optical material of PSb using the first-principles calculation method based on the density functional theory.The main contents can be summarized as follows:1.The crystal structure,phonon spectrum,stability,electronic properties,light absorption and photocatalytic properties of RbSnX3(X=Cl,Br,I)are studied under high pressure.Two phases of Cm and I4mm are predicted by the developed crystal structure analysis based on particle swarm optimization CALYPSO under different pressures.The calculation results of the phonon spectra show that there is no imaginary frequency in the two phases,indicating that the predicted structures are dynamically stable.The calculation results of the optical properties show that the Cm and 14mm phases have good light absorption and photocatalytic properties,and the strains can modulate the bandgaps and band edge positions.The results indicate that the band edges straddle water redox potentials are more easily and the absorption property can be improved effectively.2.The electronic structure,kinetic stability,light absorption and photocatalytic properties of the single-layer two-dimensional material PSb are studied using first-principle calculations.The calculation results show that PSb is dynamically stable and has a suitable optical basic band gap.PSb has strong light absorption and photocatalytic water splitting potential in the visible region to the far ultraviolet region,indicating that PSb is promising candidate for light absorption and photocatalyst.