The impact of post-treatments such as annealing, light-soaking and heat-light soaking on film properties and cell performance of ZnS(O,OH)/Cu(In,Ga)Se-2 solar cells were investigated, when ZnS(O,OH) buffer layer was deposited using a thioacetamide (TAA)-ammonia based chemical solution. Chemical bath deposition (CBD) time was shortened to one seventh by combination of a thinner buffer layer and TAA-ammonia based high-rate CBD, as compared to conventional thiourea (TU)-ammonia based CBD process. The ZnO:B window layer was deposited by metal organic chemical vapor deposition (MOCVD) in order to avoid plasma-damage during subsequent sputtering process. An optimum CIGS solar cell fabricated using 50 nm-thick ZnS(O,OH) buffer layer yielded a total area efficiency of 18.8% after heat-light soaking treatiment for 80 mm at 130 degrees C under AM1.5, 100 mW/cm(2) illumination. The influence of post-treatments on the compositional changes of the ZnS(O,OH) buffer layer, which affect the conduction band offset (CBO) at the CIGS/ZnS(O,OH) interface, are also discussed on the basis of X-ray photoelectron spectroscopy(XPS) analysis. (C) 2014 Elsevier B.V. All rights reserved.