The History of Photovoltaics with Emphasis on CdTe Solar Cells and Modules

TLDR

Cadmium telluride thin‑film photovoltaics have matured over four decades to compete with silicon, thanks to consolidated production processes. The study surveys literature and laboratory results to present fabrication processes for CdTe polycrystalline thin‑film cells and modules. The authors analyze substrate choices, layer structures, interface engineering, production tricks, industrial manufacturing steps, and environmental life‑cycle aspects of CdTe modules. Laboratory CdTe cells achieve about 22 % efficiency, while fully automated modules exceed 18 %.

Abstract

Among thin-film photovoltaic 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%. This success represents the result of over 40 years of research, which led to effective and consolidated production processes. Based on a large literature survey on photovoltaics and on the results of research developed in our laboratories, we present the fabrication processes of both CdTe polycrystalline thin-film solar cells and photovoltaic modules. The most common substrates, the constituent layers, their interaction, the interfaces and the different “tricks” necessary to obtain highly efficient devices will be analyzed. A realistic industrial production process will be analytically described. Moreover, environmental aspects, end-of-life recycling and the life cycle assessment of CdTe-based modules will be deepened and discussed.