M.Sc. / As environmental and energy resource concerns have increased, greater emphasis has been placed on development of renewable energy resources such as photovoltaic electric generators. CuInSe 2/ZnO heterojunction solar cells are currently one of the most promising technologies to produce economically viable, clean electrical energy. The reaction of metallic alloys containing copper and indium to a selenium-containing atmosphere is by far the most promising industrial process. In this study ; copper-indium metallic precursors were prepared by electron-beam evaporation. The selenization process was conducted in vacuum in elemental Se vapour and in the presence of a H 2Se/Ar gas mixture at atmospheric pressure. Attention was given to the optimization of the structural features of the metallic alloys as well as the selenization parameters. Structural analysis revealed that the number of multilayers in , the precursor stack significantly influence the morphological features of the absorber films after selenization. The reaction temperature and reaction periods during the selenization process critically influenced the reaction kinetics of metallic phases. In the case of selenization in elemental Se vapour, temperatures as high as 550°C were required to convert the metallic alloys into fully reacted semiconductor thin films. Selenization in the presence of H2Se gas was more reactive and temperatures around 450°C resulted in the complete formation of CuInSe2. In the majority of cases, traces of CuSe were detected in the bulk of the material by XRD studies. The presence of the Cu-rich binary phases rendered solar cell devices useless. After removal of these detrimental segregated phases by KCN etching, glass/Mo/CuInSe2/CdS/ZnO solar cell devices reached conversion efficiencies around 8%.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:3446 |
| Date | 03 September 2012 |
| Creators | Nel, George |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
Page generated in 0.0019 seconds