The aim of the present contribution is to give a review on the recent work concerning Cd-free buffer and window layers in chalcopyrite solar cells using various deposition techniques as well as on their adaptation to chalcopyrite-type absorbers such as Cu(In,Ga)Se 2 , CuInS 2 , or Cu(In,Ga)(S,Se) 2 . The corresponding solar-cell performances, the expected technological problems, and current attempts for their commercialization will be discussed. The most important deposition techniques developed in this paper are chemical bath deposition, atomic layer deposition, ILGAR deposition, evaporation, and spray deposition. These deposition methods were employed essentially for buffers based on the following three materials: In 2 S 3 , ZnS, Zn 1 À x Mg x O.

No abstract

No abstract

Thin-film solar cells have been fabricated from Cu(InGa)Se2 films which were deposited by four-source elemental evaporation with [Ga]/([In]+[Ga]) from 0.27 to 0.69 corresponding to a band gap from 1.16 to 1.45 eV. The films were intentionally deposited with no grading of the Ga and In to avoid gradients in their electrical and optical properties. X-ray diffraction, energy-dispersive x-ray spectroscopy, and Auger electron spectroscopy show that the films have uniform composition with no change in structure and morphology. Glass/Mo/Cu(InGa)Se2/CdS/ZnO devices have open-circuit voltage increasing over the entire band gap range to 788 mV and 15% total area efficiency for band gap less than 1.3 eV, or [Ga]/([In]+[Ga]) less than 0.5. A decrease in device efficiency with higher Ga content is caused primarily by a lower fill factor. Analysis of current–voltage and quantum efficiency measurements show that this results from a voltage-dependent current collection.