Collaborative Project 2: Novel Processes and Materials for Fabrication of Photovoltaic Devices
Kenneth Carter (Polymer Science & Engineering), D. Venkataraman (Chemistry), Marc Achermann (Physics)    Click on the faculty name to view their profile.

Nanostructured semiconductor materials exhibit interesting optical, electronic, and catalytic properties. Structured semiconductor films with dense arrays of features at the 10-50-nm scale have shown considerable promise for use in photovoltaic devices.^1-5 Complex sub-micron patterns can be made by classic photolithography as well as newer methods such as microcontact printing of self-assembled monolayers, polymer brushes, block copolymer self-assembly and a variety of imprint techniques.^6-8 Over the past several years we have developed a nano-contact molding (NCM) imprint lithographic technique for the replication of nm-scale features using functional crosslinked polymeric materials. This process offers many advantages in terms of cost and versatility.

We will use our NCM technique to create inorganic semiconductor nanostructures.^9-10 Key organic molecules attached to the semiconductor surface will serve as a reactive layer with grafting sites for the in-situ polymerization. The covalent grafting of polymer to the inorganic semiconductor surface by this technique will ensure intimate contact between these two materials. We initiated this collaboration in 2008 and it has been a success. We have made exciting discoveries in the use of NCM to template substrates for the creation of useful inorganic structures through electrodeposition. Much work needs to be done in this area and the REU students will be expected to continue to advance this exciting new area of research.

• Imprinting of Semiconductor Nanostructures: An REU student in the Carter group will fabricate the semiconductor nanostructures by creating molds and transferring the mold patterns into the semiconductor nanostructures.
• Electrodepostion and Synthesis of Coupling Reagents: An REU student in the Venkataraman group will prepare a series of coupling reagents to be attached to the semiconductor surface.
• Photophysics of Semiconductors:  An REU student in the Achermann group will study the photophysics and charge carrier-dymanics in these nanostructure

Collaborative Effort: The three REU students will work together to apply the coupling reagents to the surface of the patterned semiconductor nanostructures in order to prepare the scaffolds, then perform surface analysis by UV-Vis, IR, ellipsometry, electron microscopy and atomic force microscopy (AFM).


1. Benanti, T. L.; Kalyadjian, A.; Venkataraman, D. "Protocols for Efficient Postpolymerization Functionalization of Regioregular Polythiophenes" Macromolecules 2008, 41, 8312-8315.

2. Benanti, T. L.; Venkataraman, D. "Organic Solar Cells: An Overview Focusing on Active Layer Morphology" Photosynthesis Res. 2006, 87, 73-81.

3. Coakley, K. M.; McGehee, M. D. "Conjugated Polymer Photovoltaic Cells" Chem. Mater. 2004, 16, 4533-4542.

4. Huynh, W. U.; Dittmer, J. J.; Alivisatos, A. P. "Hybrid Nanorod-Polymer Solar Cells" Science 2002, 295, 2425-2427.

5. Kannan, B.; Castelino, K.; Majumdar, A. "Design of Nanostructured Heterojunction Polymer Photovoltaic Devices" Nano Letter 2003, 3, 1729-1733.

6. Lincot, D. "Electrodeposition of Semiconductors" Thin Solid Films 2005, 487, 40-48.

7. Lincot, D.; Kampamann, A.; Mokili, B.; Vedel, J.; Cortes, R.; Frooment, M. "Epitaxial Electrodeposition of CdTe-Films on Inp from Aqueous-Solutions - Role of a Chemically Deposited CdS Intermediate Layer," Appl. Phys. Lett. 1995, 67, 2355-2357.

8. Ravirajan, P.; Peiro, A. M.; Nazeeruddin, M. K.; Graetzel, M.; Bradley, D. D. C.; Durrant, J. R.; Nelson, J. "Hybrid polymer/zinc oxide photovoltaic devices with vertically oriented ZnO nanorods and an amphiphilic molecular interface layer," J. Phys. Chem. B 2006, 110, 7635-7639.

9. Moran, I. W.; Briseno, A. L.; Loser, S.; Carter, K. R. "Device Fabrication by Easy Soft Imprint Nano-Lithography" Chem. Mater. 2008, 20, 4595-4601.

10. von Werne, T. A.; Germack, D. S.; Hagberg, E. C.; Sheares, V. V.; Hawker, C. J.; Carter, K. R. "A Versatile Method for Tuning the Chemistry and Size of Nanoscopic Features by Living Free Radical Polymerization" J. Am. Chem. Soc. 2003, 125, 3831-3838

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