Photovoltaic devices based on Cu(In,Ga)Se2 (CIGSe) thin films are now among the most attractive non-Si alternatives. The key to their recent efficiency gain is a post-deposition treatment (PDT) with alkali salts. RbF was demonstrated as the most efficient alkali salt for the PDT of coevaporated CIGSe- based solar cells. It is known that the effectiveness of the RbF-PDT strongly depends on the composition of the underlying CIGSe and the formation of secondary phases such as RbInSe2 during the PDT . To clarify this effect, RbF- and RbInSe2- covered CIGSe absorbers were investigated by means of bulk and surface sensitive methods. Kelvin probe and photoelectron yield spectroscopy techniques were applied to determine the work function and the valence band edge (VBM) of the unexposed to air RbInSe2/CIGSe interface as well as its energy band diagram as a function of the RbInSe2 deposition time. These changes are correlated to the chemical composition of the surface of the RbInSe2-covered CIGSe given by Xray photoelectron spectroscopy analysis and compared to those of bare and RbF- covered CIGSe. Since both RbF- and RbInSe2- covered CIGSe have to be exposed to air before being finished into solar cell devices, we also investigated the effect of air exposure on the chemical, electronic and structural properties of covered CIGSe absorbers. For that, additional Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays Spectroscopy (EDS) investigations were undertaken.