Post-treatment effects on ZnS(O,OH)/Cu(In,Ga)Se2 solar cells deposited using thioacetamide-ammonia based solution

• Post-treatment effects on ZnS(O,OH)/CIGS device deposited using TAA-ammonia based CBD.
• A 18.8% efficiency CBD-ZnS(O,OH)/CIGS thin film solar cell by heat-light soaking treatment.
• ZnS(O,OH)/CIGS solar cells after HLS could be represented by a clear P-N junction.

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)Se2 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 treatment for 80 min at 130 °C under AM1.5, 100 mW/cm2 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.

The impacts of post-treatment on cell performance of ZnS(O,OH)/Cu(In,Ga)Se2 solar cells were investigated, when ZnS(O,OH) buffer layer was deposited using a thioacetamide (TAA)-ammonia based chemical solution. All parameters especially FF increased drastically after heat-light soaking treatment. Although the cell efficiency showed slight increase after the HS post-treatment, the increase in cell efficiency was much more important after the LS (from η=8.0% to 12.0%) and HLS post-treatments (from η=7.8% to 16.0%), respectively.Figure optionsDownload as PowerPoint slide