Atomic layer deposition of ZnInxSy buffer layers for Cu(In,Ga)Se2 solar cells

International audienceWe report in this paper the use of ZnInxSy films deposited by atomic layer deposition as cadmium free buffer layer in Cu(In,Ga)Se2 (CIGS) solar cells. Buffer layers with different In/(In + Zn) ratios over the whole composition range were prepared on glass substrate and characterized optically by transmission and reflection measurement and electrically by steady state photoconductivity and modulated photocurrent. CIGS solar cells were prepared with the different buffer layers and characterized. A compromise between the properties of In2S3 and ZnS was found for intermediate compositions as aimed for this study. Best efficiencies were obtained for intermediate composition (In/(In + Zn) close to 28 at. %) which also allows a higher open circuit voltage. Solar cell simulations allowed to point out the major role played by interface defect states in these devices