A brief overview of the main photovoltaic technologies is chronologically presented. Single-crystal and multi-crystalline, epitaxial and thin film inorganic materials are widely used as absorbers in high efficiency solar cells and modules. A schematic representation of the principal devices developed in more then 70 years of research will be displayed and commented. Among thin-film technology, cadmium telluride (CdTe) has achieved a truly impressive development that can commercially compete with silicon, which is still the king of the market. Solar cells made on a laboratory scale have reached efficiencies close to 22%, while modules made with fully automated in-line machines show efficiencies above 18%. Based on the research developed in our laboratory, the fabrication processes of both CdTe polycrystalline thin-film solar cells and photovoltaic modules are critically discussed. The most common substrates, the constituent layers and their interaction, the interfaces and the different “tricks” commonly used for obtaining highly efficient devices will be analyzed. A realistic industrial production process will be analytically described.
Photovoltaics with Emphasis on CdTe Solar Cells and Modules
