| AVS 58th Annual International Symposium and Exhibition | |
| Energy Frontiers Focus Topic | Wednesday Sessions |
| Session EN1+TF-WeA |
| Session: | Thin Film Chalcogenide Solar Cells (CIGS, CZTS, CdTe and Related Materials) |
| Presenter: | Ankur Khare, University of Minnesota |
| Authors: | A. Khare, University of Minnesota Y. Li, University of Minnesota B. Chernomordik, University of Minnesota B.S. Tosun, University of Minnesota A.W. Wills, University of Minnesota D.J. Norris, University of Minnesota E.S. Aydil, University of Minnesota |
| Correspondent: | Click to Email |
Copper zinc tin sulfide (Cu2ZnSnS4 or CZTS) is emerging as a promising photovoltaic material for thin film solar cells. CZTS has a band gap of ~1.4 eV, the ideal value for converting the maximum amount of energy from the solar spectrum. In addition, CZTS has a high absorption coefficient (> 104 cm-1 in the visible region of the electromagnetic spectrum) and its constituent elements are all abundant in the earth’s crust and are non-toxic. We have synthesized CZTS nanocrystals from metal dithiocarbamate complexes. The diameter of the nanocrystals can be varied from 2-7 nm by changing the temperature and synthesis time. A suite of methods including Raman spectroscopy, optical absorption, electron energy loss spectroscopy and X-ray diffraction were used to characterize these nanocrystals and show that they are phase-pure CZTS. Nanocrystals with diameters less than 3 nm exhibit quantum confinement. These quantum dots were used to assemble quantum dot solar cells. In a second approach to making solar cells, thin films of CZTS nanocrystals are annealed to form thin films with large grains. Nanocrystals melt at temperatures much less than the bulk temperature and recrystallize to yield larger CZTS grains. These films were then used for making conventional thin film solar cells.