Influence of CdTe thickness on structural and electrical properties of CdTe/CdS solar cells

Due to its high scalability and low production cost, CdTe solar cells have shown a very strong potential for large scale energy production. Although the number of modules produced could be limited by tellurium scarcity, it has been reported that reducing CdTe thickness down to 1.5 μm would solve this issue. There are, however, issues to be considered when reducing thickness, such as formation of pinholes, lower crystallization, and different possible effects on material diffusion within the interfaces. In this work, we present the study of CdTe solar cells fabricated by vacuum evaporation with different CdTe thicknesses. Several cells with a CdTe thickness ranging from 0.7 to 6 μm have been fabricated. The deposition process has been optimized accordingly and their physical and electrical properties have been studied. Thin cells show a different electrical behavior in terms of open circuit voltage and fill factor. Efficiencies range from 7% for thin CdTe cells to 13.5% for the standard thickness.

► Ultra thin CdTe absorbers have been prepared and studied.
► Grain size is depending on the CdTe thickness but spread in the grains increases.
► Lattice parameter is reduced only for ultra thin CdTe.
► The band gap reveals an intermixed CdTe absorber.
► The reason for lower efficiency of ultra thin CdTe is explained.