Jaron Van Dijken Electrical & Computer Engineering University of Alberta June 11, 2009
Outline Building a case for next gen solar technology Fundamentals of Organic Photovoltaics (OPV) Challenges, and status of OPV technology Efficiency limits Commercialization efforts
Building a case for next gen solar... Solar & PV a pipedream, or could it really work...? More solar energy reaches the earth s surface in one hour than what the entire world uses in one year The electricity demands of the entire U.S. could be met by covering a 100km x 100km area with solar cells at a photoconversion efficiency of 15%
Building a case for next gen solar... Solar & PV a pipedream, or could it really work...? More solar energy reaches the earth s surface in one hour than what the entire world uses in one year The electricity demands of the entire U.S. could be met by covering a 100km x 100km area with solar cells at a photoconversion efficiency of 15% 17.5 % of the Mojave desert 0.1 % of the U.S. land mass
Building a case for next gen solar... Solar & PV a pipedream, or could it really work...? More solar energy reaches the earth s surface in one hour than what the entire world uses in one year The electricity demands of the entire U.S. could be met by covering a 100km x 100km area with solar cells at a photoconversion efficiency of 15% Yes we can... 17.5 % of the Mojave desert 0.1 % of the U.S. land mass
Building a case for next gen solar... Crystalline Silicon technology is mature Physics is well-understood Processing is irreducibly complex Economies of scale already reached...still expensive
Building a case for next gen solar... Crystalline Silicon technology is mature Further cost reduction is unlikely, demanding the development of other PV technologies S.E. Shaheen, et. al. MRS Bulletin 30 (2005)
Organic PV What is it? Certain organic molecules and polymers: Capture light efficiently (good absorption) Have semiconducting properties Can be processed in solution, at room temperature! (some) Hold the promise of ultra-low-cost solar panels T. Ameri, et. al. Energy & Environmental Science 2 (2009)
Organic PV What is it? Certain organic molecules and polymers: Capture light efficiently (good absorption) Have semiconducting properties Can be processed in solution, at room temperature! (some) Hold the promise of ultra-low-cost solar panels Other major advantage: Lightweight and flexible Potential for portable, user-friendly, lightweight, easily integrated consumer products
2008 Organic PV History 2007 Efficiencies of OPV devices are quite poor... We re just getting started: Activity has only picked up in last 5 years or so Device physics is only reasonably well understood. Commercialization has barely begun no benefit from economies of scale The potential is great... T. Ameri, et. al. Energy & Environmental Science 2 (2009)
Organic PV Fundamentals Limited exciton diffusion length F. Yang, et. al. Nature Materials 4 (2005)
Organic PV Fundamentals Limited exciton diffusion length Bulk heterojunction concept F. Yang, et. al. Nature Materials 4 (2005)
Organic PV Fundamentals Limited spectral coverage for single layer Tandem cell T. Ameri, et. al. Energy & Environmental Science 2 (2009)
Status of OPV technology Polymeric cells (Alan Heeger s group) Small molecule cells (Stephen Forrest s group) Single device Tandem device 5.5% (1) 5.0% (3) 6.5% (2) 5.7% (4) A major improvement from 1.0 %, but need ~ 10 % to be competitive in the market 1. J. Peet, et. al. Nature Materials 6 (2007) 2. J.Y. Kim, et. al. Science 317 (2007) 3. J. Xue, et. al. J. Appl. Phys. 98 (2005) 4. J. Xue, et. al. Appl. Phys. Lett. 85 (2004)
Efficiency limits Are 10% organic solar cells realistic? What is theoretically possible? From Progress in Photovoltaics: Research and Applications (2007): Single device: 5.8% (current materials) 15.2% (optimistic) Tandem device: 10.1% (realistic) 23.2% (optimistic) B. Minnaert, M. Burgelman. Prog. Photovolt: Res. Appl. 15 (2007)
Commercialization - GPEC www.globalphotonic.com Organic Photovoltaics (OPV TM s) Based on the small molecule work of Stephen Forrest s group Flexible and lightweight, semi-transparent (window tinting) Aesthetically pleasing (color tunable) Photo Fuel TM A Cost Efficient and Environmentally Benign Method of Producing Hydrogen Essentially use their OPV technology to power the electrolysis of water into hydrogen and oxygen
Commercialization - Konarka R. Gaudiana, C.J. Brabec. Nature Photonics 2 (2008)
Commercialization - Konarka www.konarka.com
Summary Organic photovoltaics uses carbon-based materials to make ultra-low-cost solar panels Research in this area expanding extremely quickly Still young...8 years or so Current photoconversion efficiencies are 5~6 %; improvements needed for competitive market entry Large-scale commercialization has recently begun, Konarka being the leader
Yes we can... www.konarka.com