Nearly carbon-free printable CIGS thin films for solar cell applications

In order to fabricate low cost and printable CuInxGa1−xSeyS2−y (CIGS) thin film solar cells, a precursor solution based method was developed. Particularly, in this method, nearly carbon-free CIGS film was obtained by applying a three-step heat treatment process: the first for the elimination of carbon residue by air annealing, the second for the formation of CIGS alloy by sulfurization, and the third for grain growth and densification in the CIGS film by selenization. The film also revealed very large grains with a low degree of porosity, similar to those produced by the vacuum based method. A solar cell device with this film showed current–voltage characteristics of Jsc=21.02 mA/cm2, Voc=451 mV, FF=47.3%, and η=4.48% at standard conditions.

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► A precursor solution based method was developed for low cost and printable CuInxGa1−xSeyS2−y (CIGS) thin film solar cells.
► Nearly carbon-free CIGS film was obtained by applying a three-step heat treatment process.
► Very large grains with a low degree of porosity after the three-step heat treatment process.
► Solar cell device with this film showed efficiency of 4.48% at standard conditions.