Thin light-active layers of the CuInSe2 solar cell were prepared on Mo-coated sodalime glass substrates by one-step electrodeposition and post-annealing. The structure, morphology, and composition of CuInSe2 film could be controlled by deposition parameters, such as the composition of metallic precursors, the concentration of complexing agents, and the temperature of post-annealing with elemental selenium. A dense and uniform Cu-poor CuInSe2 film was successfully obtained in a range of parametric variation of electrodeposition with a constant voltage of -0.5 V vs. a Ag/AgCl reference electrode. The post-annealing of the film at high temperature above 500℃ induced crystallization of CuInSe2 with well-developed grains. The KCN-treatment of the annealed CuInSe2 films further induced Cu-poor CuInSe2 films without secondary phases, such as Cu2Se. The structure, morphology, and composition of CuInSe2 films were compared with respect to the conditions of electrodeposition and post-annealing using SEM, XRD, Raman, AES and EDS analysis. And the conditions for preparing device-quality CuInSe2 films by electrodeposition were proposed.

In this paper, CuInSe2 thin film was prepared by use of the co-evaporation method with the variation of the substrate temperature in the range of 100℃ to 400℃. The film was annealed at 300℃ for an hour in a vacuum chamber at 3×10-4 Pa. After annealing, the thin film prepared at the substrate temperatures of 100℃ and 200℃ was observed. The XRD (x-ray diffraction) pattern of sample prepared at 100℃ showed the single phase formation of CuInSe2. However, at 200℃, there was no apparent difference in the XRD pattern except a variation in the intensity of the peak. As the annealing treatment of substrate improved the crystal structure of the film, it affected to the increase of an electron mobility, resulted in an increase in conductivity and a decrease in resistance. As a results, when the substrate temperature was at 200℃ and 300℃, the sheet resistance was 1.534 n/and 1.554 n/, respectively, and the resistivity was 1.76×10-6 n·㎝ and 1.7210-6 n·㎝, respectively. From the absorption spectrum measurements, there was no variation between the before and after annealing conductions. And it means that the annealing step does not affect the thickness of the thin film.

Citations

• Effect of Bi incorporation and temperature on the properties of sprayed CuInS2 thin films
  C. Mahendran, N. Suriyanarayanan
  Physica B: Condensed Matter.2013; 408: 62.     CrossRef
• Effect of temperature on structural, optical and photoluminescence properties of antimony (Sb) doped polycrystalline CuInS2 thin films prepared by spray pyrolysis
  N. Suriyanarayanan, C. Mahendran
  Materials Science and Engineering: B.2011; 176(5): 417.     CrossRef
• A Study on Copper Selenide Thin Films for Photovoltaics by a Continuous Flow Microreactor
  Chae Rin Kim, Seung Yeol Han, Chih Hung Chang, Tae Jin Lee, Si Ok Ryu
  Molecular Crystals and Liquid Crystals.2010; 532(1): 39/[455].     CrossRef