First principle studies on the optoelectronic properties of rubidium lead halides
Entirely inorganic perovskites have attracted enormous attention of late owing to their outstanding applications in optoelectronics including highly stable perovskite solar cells. In-depth understanding of the optoelectronic and transport properties of such materials are vital for practical implementation of the same. The carrier transport properties of the electronic devices based on perovskite materials significantly depend on the effective mass of the respective charge carriers. Here, we have performed first principle calculations with FP-LAPW method for the orthorhombic rubidium lead halide structures (\ch{RbPbX_3}, where \ch{X=I,Br,Cl}) to study the optoelectronic and transport properties. The effective mass of electron (hole) is found to be minimum for \ch{RbPbBr_3} (\ch{RbPbI_3}), suggesting an efficient transport of electrons (holes) in the corresponding materials. Our calculated values such as the dielectric constants, refractive indices, absorption coefficients and reflectivities show good agreement with reported experimental data. To the best of our knowledge, ab-initio study of electronic and optical properties of \ch{RbPbBr_3} \& \ch{RbPbCl_3} in orthorhombic phase (\ch{NH_4CdCl_3} type structure) is reported for the first time.