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New Materials and Nanostructuring for Photovoltaics
[Carl Hagglund, Steven M. Herron, Thomas Joseph, Artit Wangperawong]

New Materials and Methods
We are studying new photovoltaic materials comprised of earth-abundant and non-toxic elements. We are currently focusing on materials that are similar to CIGS but use combinations of other elements to yield similar band gaps and absorption. Of current interest is copper zinc tin sulfide (CZTS), iron sulfide and tin sulfide. Sulfur is nearly four orders of magnitude more abundant than selenium, and hydrogen sulfide gas, often used for processing of sulfides is much less toxic than hydrogen selenide. We are studying low cost methods of processing, including chemical bath deposition (CBD) with post-deposition sulfurization heat treatments.

Nanostructuring
We also aim to boost the efficiency of our solar cells by engineering nanoscale devices that offer excellent light absorption and subsequent charge extraction. Many of the materials used in inexpensive thin film devices exhibit a large mismatch between electronic and photonic length scales. The typical absorption depth in photovoltaic materials is significantly longer than the electronic (minority carrier) diffusion lengths. For this reason, it is challenging to attain high operational efficiencies. Nanostructured devices can help address these problems by enhancing light absorption in thin active regions.

Copper-Zinc-Tin-Sulfide Structure

Publications

  1. Artit Wangperawong and Stacey F. Bent, Three-dimensional nanojunction device models for photovoltaics, Appl. Phys. Lett. 98, 233106 (2011).

  2. Artit Wangperawong and Stacey F. Bent, Modeling Performance of Three-Dimensional Nanojunction Photovoltaic Devices, 37th IEEE Photovotaic Specialists Conference, (2011).

  3. Steven M. Herron, Artit Wangperawong and Stacey F. Bent, Chemical Bath Deposition and Microstructuring of Tin (II) Sulfide Films for Photovoltaics, 37th IEEE Photovotaic Specialists Conference, (2011).

  4. Artit Wangperawong, Jeffrey S. King, Steven M. Herron, Benjamin P. Tran, Kristine Pangan-Okimoto and Stacey F. Bent, Aqueous Bath Process for Deposition of Cu2ZnSnS4 Photovoltaic Absorbers, Thin Solid Films 519, 2488-2492 (2011).

  5. Artit Wangperawong, Jeffrey S. King, Steven M. Herron, Benjamin P. Tran, Kristine Pangan-Okimoto and Stacey F. Bent, A Chemical Bath Process for Depositing Cu2ZnSnS4 Photovoltaic Absorbers, 35th IEEE Photovotaic Specialists Conference, 001986-001989 (2010).

Much of our research is supported as part of the Center on Nanostructuring for Efficient Energy Conversion (CNEEC) at Stanford University, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Other support comes from the National Science Foundation under grant CBET 0930098.

                             

 

 

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