Effect of annealing on conversion efficiency of nanostructured CdS/CuInSe2 heterojunction thin film solar cell prepared by chemical ion exchange route at room temperature

We report, the effect of air annealing on solar conversion efficiency of chemically grown nanostructured heterojunction thin films of CdS/CuInSe2, such 100, 200 and 300 °C air annealed thin films characterized for physicochemical and optoelectronic properties. XRD pattern obtained from annealed thin films confirms tetragonal crystal geometry of CuInSe2 and an increase in average crystallite size from 16 to 32 nm. An EDAX spectrum confirms expected and observed elemental composition in thin films. AFM represents high energy induced grain growth and agglomeration due to polygonization process. Increase in optical absorbance strength and decrease in energy band gap from 1.36 to 1.25 eV is observed. Increase in charge carrier concentration from 2 × 1016 to 8 × 1017 cm−3 is observed as calculated from Hall effect measurements and an enhancement in solar conversion efficiency from 0.26 to 0.47% is observed upon annealing.

The CdS/CuInSe2 heterojunction thin film prepared by chemical ion exchange route at room temperature and annealed at 100, 200 and 300 °C shows increase in conversion efficiency and carrier concentrations.Figure optionsDownload as PowerPoint slideHighlights
► Nanostructured CdS/CuInSe2 thin film can be prepared by chemical ion exchange method.
► Composition and surface can be modified by annealing at 100, 200 and 300 °C.
► Solar energy conversion efficiency increases from 0.26, 0.33, 0.39 and 0.47% upon annealing.
► Observed results confirms probable use of annealing for solar applications.