CdTe-Based Photodetectors and Solar Cells

In this chapter we will show how much appreciated were the electro-optical characteristics of one of the most widely used semiconductors of the II-VI family, Cadmium Telluride or CdTe. High quality single crystals with industrially appreciable dimensions have been easily obtained since the beginning of the CdTe epopee. Exploiting its very high transparency in the mid-infrared it was firstly employed as window for i.r. laser applications. Its role, as a material for developing electro-optical modulators needed for the evolution of power CO2-based lasers, was crucial. In more modern times, with the advent of nanotechnologies, CdTe has found considerable success as a UV-Vis photodetector if used in the form of dots, ribbons, belts and, more in general, when it is possible to exploit quantum confinement in reduced dimensions. But where CdTe has been most successful is in the photovoltaic field, where solar cells and photovoltaic modules, with conversion efficiency greater than 22% and 19% respectively, have been made. To date, among thin-film technologies, CdTe-based modules occupy the first place on the market and more than 8% globally. We will talk about this and much more in the rest of this chapter by going into the detail of the photodetectors and, mainly, of the solar cells, revealing the smartest tricks normally used to make these devices sustainable, efficient and cost-effective.