- Kesterite ( mineral )
990 ° C.
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Copper -zinc tin sulfide ( CZTS abbreviated from English copper, zinc, tin, sulfur ) is a semiconducting compound of copper, zinc, tin and sulfur. Being explored for use in thin film solar cells.
CZTS crystallizes similar Stannite ( Cu2FeSnS4 ) and Kesterite ( Cu2 ( Zn, Fe) SnS4 ) in the tetragonal crystal system with the space group and the lattice parameters a = 0.5427 nm and c = 1.0871 nm In this form, the material has a direct band transition with a band gap energy of 1.4-1.5 eV.
The relatively good physical properties (size of the band gap ), among others, an application results in an electrically active layer in thin film solar cells (see photovoltaics). Depositing CZTS layers can be carried out via various coating processes, such as sputter deposition, thermal evaporation, laser ablation, or chemical vapor deposition ( CVD). In the foreground for a commercial use, however, is not so much the band gap, the also offer various other materials, but the absence of rare or toxic elements such as indium or mercury.
Solar cells based on CZTS base will still be in the area of research. Researchers at the Technical University of Tallinn developed powder -based mono-particle membrane solar cells, which also contain selenium ( Se). This is also referred to with CZTSSe material can be in its band gap continuously between that of the pure sulfide ( CZTS, luminescence peak at 1.3 eV ) and that of the pure selenide ( CZTSe, luminescence peak at 0.95 eV) to move. With these solar cells, the first independently certified efficiency of CZTS solar cells in 2009 at 5.9 % was reached. The TUT spin crystalsol developed on this basis a module production in Estonia and Austria. Of particular practical interest is the extremely low temperature coefficient of this solar cell material, which is 0.013 % / K, well below the other solar cell materials. Researchers from IBM achieved with applied from hydrazine solutions solar cell efficiencies of 9.6 percent for pure sulfide ( CZTS ) and of 9.3 percent for pure selenide ( CZTSe ).