Aug 22 2013
Topics Covered
Description
Applications
Chemical Properties
Electrical Properties
Mechanical and Optical Properties
Recent Developments
Description
Copper zinc tin sulfide is a quaternary semiconducting compound that has favorable optical and electronic properties, similar to copper indium gallium selenide. It can be obtained from chalcopyrite by substituting the trivalent In/Ga with a bivalent Zn and IV-valent Sn. It can be prepared by a variety of vacuum and non-vacuum techniques and serves as an efficient semiconductor for thin film photovoltaics.
Applications
Copper zinc tin sulfide can be used as a low cost absorber layer substituting for copper indium gallium selenide in the thin film solar cells. It can lead to production of non-toxic thin film solar cells with high absorption coefficients.
Chemical Properties
The chemical properties of copper zinc tin sulfide are provided in the table below:
|
Chemical Properties |
|
Chemical Formula |
Cu2ZnSnS4 |
|
Molecular Weight |
439.471 |
|
CAS No. |
12158-89-3 |
|
Group |
Copper – 11
Zinc – 12
Tin – 14
Sulfur - 16 |
|
Crystal Structure |
Tetragonal |
|
Lattice Constant |
a = 0.5435 nm
c = 1.0843 nm |
Electrical Properties
The electrical properties of copper zinc tin sulfide are provided in the table below:
|
Electrical Properties |
|
Electron Affinity |
4.5 eV |
|
Dielectric Permittivity |
10 |
|
Band Gap |
1.45 eV |
|
Electron Thermal Velocity |
1 x 107 cm/s |
|
Hole Thermal Velocity |
1 x 107 cm/s |
|
Electron Mobility |
50 cm/Vs |
|
Hole Mobility |
50 cm2/Vs |
Mechanical and Optical Properties
The mechanical and optical properties of copper zinc tin sulfide are provided in the tables below:
|
Mechanical Properties |
|
Density |
4.56 g/cm3 |
|
Melting Point |
990°C |
|
Optical Properties |
|
Refractive Index |
2.07 |
Recent Developments
Z. Lin et al (2011) described a novel, environment-friendly Pt-free counter electrode for dye-sensitized solar cells based on low-cost quaternary copper zinc tin sulfide. These copper zinc tin sulfide nanocrystals were synthesized and spin-coated onto fluorine-doped tin oxide glass. The power conversion efficiency of the resulting dye-sensitized solar cells, after selenization of the CZTS semiconductor, was found to be comparable to that of the device with the Pt-free counter-electrode.
Enhancing energy/fuel efficiency by converting waste heat into electricity by using thermoelectric materials is of great interest owing to its reliability and simplicity. However, most of the thermoelectric materials are composed of either toxic or scarce elements. Yang H et al (2012) reported the experimental realization of using abundant and nontoxic copper zinc tin sulfide nanocrystals for potential thermoelectric applications.
These nanocrystals can be synthesized in large quantities from solution phase reaction and compressed into robust bulk pellets through spark plasma sintering and hot press. In addition, they performed electrical and thermal measurements from 300 to 700K to understand the electron and phonon transports. The results showed that extra copper doping during the nanocrystal synthesis enhances the performance of thermoelectric materials.