Organic Solar Cells

Introduction

Organic solar cells are a compelling solar energy harvesting technology that might deliver electrical energy at a very low cost per kWh. A low materials cost and very high throughput processing make this possible. However, these devices are still in the research stage and more work is required to:

• Demonstrate higher efficiencies: today's best organic solar cells convert sunlight into electrical power with efficiencies up to 6%. Most likely, efficiencies >10% are required. Fortunately, these efficiencies are within the realm of possibilities for such materials. A realistic estimate for an advanced (multijunction) organic solar cell predicts that efficiencies well over 20% may be possible provided the required materials are developed.
  
• Demonstrate useful cell durability: when something goes on a roof or larger scale PV installation, you want to make sure it's going to last since replacing the module is going to be costly. Packaging to seal the cells against oxygen and water helps a lot in improving the cell lifetime, but given the cost sensitivity of organic solar cells, the best packages are probably not an option. We therefore concentrate on the most stable materials known and try to figure out how to make efficient cells from these materials.
  
• Demonstrate manufacturability: all of us in the organic solar cell field talk about high throughput processing, but there is no published report on how fast you can deposit an organic solar cell using either solution-phase or vacuum processing.

Projects

• Light trapping in organic solar cells (Seung Rim)
  
• Improved open circuit voltages (Albert Liu and Junbo Wu)
  
• Low-bandgap materials (Albert Liu and Junbo Wu)
  
• High-throughput deposition of organic solar cells (Albert Liu)
  
• Fiber-based organic solar cells (Whitney Gaynor)
  
• Organic solar cells on metal foil (Whitney Gaynor)
  
• Parallel and series-connected multijunction organic solar cells (Seung Rim and Jung-Yong Lee)
  
• Cheaper and better transparent electrodes (Jung-Yong Lee and Junbo Wu)
• Plasmonic light concentration (Shigeo Fujimori, Jung-Yong Lee and Rostam Dinyari)
• Physics and device simulation of nanostructured organic solar cells (Shanbin Zhao, Seung Rim and Albert Liu)
  
• Organic solar cell degradation
  

Publications

Journal Publications

• J. Wu, H.A. Becerril, Z. Bao and P. Peumans, "Organic solar cells with solution-processed graphene transparent electrodes," accepted in Appl. Phys. Lett.
• S. Fujimori, R. Dinyari and P. Peumans, "Electrically-assisted aerosol deposition of metal nanoparticles," in preparation.
• S. Zhao and P. Peumans, "Simulations of carrier dynamics in bulk heterojunction organic solar cells," in preparation.
• S. Fujimori, R. Dinyari, J.-Y. Lee and P. Peumans, "Plasmonic light concentration in organic solar cells," accepted in Nanoletters.
• M. Agrawal and P. Peumans, "Broadband optical absorption enhancement through coherent light trapping in thin-film photovoltaic cells," Optics Express 16, 5385-5396 (2008). (pdf, journal link)
• S.-B. Rim and P. Peumans, "The effects of optical interference on exciton diffusion length measurements using photocurrent spectroscopy," accepted in Journal of Applied Physics.
• A. Liu, S. Zhao, S.-B. Rim, M. Koenemann, P. Erk and P. Peumans, "Control of electric field strength and orientation at the donor-acceptor interface in organic solar cells," Advanced Materials 2008, 1065-1070 (2008). ( journal link)
• J.-Y. Lee, S.T. Connor, Y. Cui and P. Peumans, "Solution-processed metal nanowire mesh transparent electrodes", Nanoletters 8, 689-692 (2008). ( pdf, journal link).
• S.-B. Rim, S. Zhao, S.R. Scully, M.D. McGehee and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Applied Physics Letters 91, 243501 (2007). ( journal link, pdf) Highlights: 2nd most downloaded paper from the Applied Physics Letters website in December 2007 ( link), and 11th in January 2008 ( link). Highlighted in Photonics Spectra.
  
• S.-B. Rim, R. F. Fink, J.C. Schoeneboom, P. Erk and P. Peumans, "Effect of molecular packing on the exciton diffusion length in organic solar cells," Applied Physics Letters 91, 173504 (2007). ( journal link, pdf)
• S. Zhao and P. Peumans, "Geminate recombination at organic semiconductor heterojunctions," submitted.
  

Conference Talks

• C. Kim, J.-Y. Lee, P. Peumans and J. Kim, "Surface plasmon polariton assisted organic solar cells," NSTI Nanotech 2008, Boston, Massachussettes, June 1-5, 2008. (Conference link, Abstract)
• S. Zhao, A. Liu, S.-B. Rim and P. Peumans, "New insight into Carrier Recombination in Organic Solar Cells," 33rd PVSC Conference, San Diego, CA, May 11-16, 2008. (Conference link)
• J.-Y. Lee, S.T. Connor, Y. Cui and P. Peumans, "Solution-processed metal nanowire mesh transparent electrodes," MRS Fall 2007, November 2007, Boston, MA [GG11.2, 10:45AM, Nov. 29].
  
• S.-B. Rim, S. Zhao, S.R. Scully, M.D. McGehee and P. Peumans, "An effective light trapping configuration for thin-film solar cells," MRS Fall 2007, November 2007, Boston, MA [H12.2, 3.45PM, Nov. 28].
  
• A. Liu, S. Zhao, S.-B. Rim, M. Koenemannm P. Erk and P. Peumans, "Control of Electric Field Strength and Orientation at the Donor-Acceptor Interface in Organic Solar Cells," MRS Fall 2007, November 2007, Boston, MA [H10.5, 11:00AM, Nov. 28].
  
• S. Fujimori, R. Dinyari, J.-Y. Lee and P. Peumans, "Electric-field-assisted aerosol deposition of metal nanoparticles for surface-plasmon-enhanced organic photovoltaic cells," Electronic Materials Conference, June 20-22, 2007, University of Notre Dame, IN.
  
• J.-Y. Lee and P. Peumans, "Subwavelength metal gratings as fleible and ransparent electrodes in organic thin-film photovoltaic cells," Electronic Materials Conference, June 20-22, 2007, University of Notre Dame, IN.
• S. Zhao and P. Peumans, “Geminate charge separation in organic bulk heterojunction photovoltaic cells,” Materials Research Society 2005 Spring Meeting, San Francisco, CA, April 2005.

Invited Talks

• P. Peumans, TBD, ICEL-7, Dresden, Germany, September 2-6, 2008. (Conference link)
• P. Peumans, "Dielectric and plasmonic approaches to enhancing the efficiency of solar cells," IEEE LEOS, Long Beach, CA, November 9-13, 2008. ( Conference link)
• P. Peumans, "Nanophotonic approaches to low-cost and high-efficiency photovoltaics," SPIE Optics + Photonics 2008, San Diego, CA, August 10-14, 2008. (Conference link)
  
• P. Peumans, TBD, OSA Integrated Photonics and Nanophotonics Research and Applications (IPNRA) Topical Meeting, July 13-16, 2008, Boston, MA.
  
• P. Peumans, "Metal nanostructures for cheaper and more efficient organic photovoltaics," Organic Microelectronics and Optoelectronics Workshop, San Francisco, CA, July 8-11, 2008. (Workshop website)
  
• P. Peumans. TBD, Technical Innovation Colloquium at Sharp America, June 27, 2008.
  
• P. Peumans, TBD, International Workshop on Organic and Organic/Inorganic Composite Optoelectronic Devices (IWOCOMD 2008), Hangzhou, China, June 5-7, 2008. (Conference link)
  
• P. Peumans, "Are nanostructures of any use in solar energy conversion?," EECS Colloquium at MIT, May 7, 2008.
  
• P. Peumans, "Exploiting the optical properties of metal nanostructures in solar cells," Foundations of Nanoscience Conference (FNANO08), Snowbird, UT, April 22-25, 2008. (Conference website)
  
• P. Peumans, "Enhancing the efficiency of solar cells using metal nanostructures," MRS Fall 2007, November 2007, Boston, MA [GG10.1, 8:00AM, Nov. 29].
• P. Peumans, "Improved light absorption, exciton diffusion and carrier separation in small molecular weight organic solar cells," MRS Fall 2007, November 2007, Boston, MA [H10.2, 9:00AM, Nov. 28].
• P. Peumans, "Nanomaterials for low-cost, high-efficiency solar cells," 2007 Nano P2 Conference, Sep. 25-26, Arlington, VA, 2007. (Conference website)
  
• P. Peumans, "The importance of unintentional doping in small molecular weight organic solar cells," SPIE Optics and Photonics 2007, August 2007, San Diego, CA.
  
• P. Peumans, "Nanoscale carrier and light transport in organic solar cells," Colloquium in Chemical Engineering and Materials Science Department, University of Minnesota, May 1, 2007.
  

Tutorials

• P. Peumans, "SC797: The science and technology of organic solar cells," SPIE Optics + Photonics 2008, San Diego, CA, August 10-14.
• P. Peumans, "SC797: The science and technology of organic solar cells," SPIE Optics and Photonics Meeting, August 2007, San Diego, CA. (pdf, SPIE Course website)
• P. Peumans, Tutorial on Organic Photovoltaics, MRS Fall Meeting 2005, Boston, MA, November 2005.
  

Project Info

• People: Whitney Gaynor, Albert Liu, Junbo Wu, Shanbin Zhao, Rostam Dinyari, Shigeo Fujimori (Toray), Jung-Yong Lee, Seung Rim
  
• Collaborators: Mike McGehee, Zhenan Bao, Max Shtein (University of Michigan), Mark Brongersma, Shanhui Fan, Steve Forrest (University of Michigan)
• Current sponsors: GCEP, BASF, DOE, NSF, Applied Materials

Resources