  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.
