Nanophotonics Class 9 Nanophotovoltaics. The world’s present sources of energy.
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Transcript of Nanophotonics Class 9 Nanophotovoltaics. The world’s present sources of energy.
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Nanophotonics
Class 9
Nanophotovoltaics
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The worlds present sources of energy
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Different sources of energy: futureoilcoalgasnuclear powerhydroelectricitybiomass (traditional)biomass (advanced)solar power (photovoltaics (PV) & solar thermal generation (CSP)solar thermal (heat only)other renewablesgeothermalwind energyGerman Advisory Council on Global Change, 2003, www.wbgu.deEJ/a PV & CSPgascoaloilsun
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+ The greenhouse effect!
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Available renewable energy sources
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Black dots:area of solar panels needed to generate all of the worlds energy
assuming 8% efficient photovoltaics Solar irradiance on earthAverage solar irradiance, W/m2.
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Solar flux distribution on earthin kWh/m2.daysource: ABB, 1998
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Ron Tandberg
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Production costs of electricityUS DOE (2002)
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Explosive growth in PV manufacturingP. Maycock, PV News (2005)
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Price per solar Watt vs. installed powerP. Maycock
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CHALLENGEHow to reduce the price/Watt of photovoltaic energy ????Increase efficiency Reduce materials costs
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Solar cell basic geometry
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Current-Voltage characteristics
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The first practical solar panel (1954)Bell Laboratories (1954)
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Si solar cell efficiencies
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Efficiency/cost of photovoltaic technologyM. Green, UNSWCrystallineSilicon cells
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Efficiency/cost of photovoltaic technologyM. Green, UNSWOrganic, thin-film cells
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Improvements in solar cell efficienciesUS DOE 2006
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Third-generation photovoltaicsM. Green, UNSW
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H. Atwater (CALTECH)Quantum defect problem
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H. Atwater (CALTECH)
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H. Atwater (CALTECH)
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Record efficiency solar cellNREL data (2005)
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Efficiency/cost of photovoltaic technologyM. Green, UNSWtandem cells
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Efficiency/cost of photovoltaic technologyM. Green, UNSWThin-film cells
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Thin-film solar cells
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Poor IR absorption in (thin-film) Si solar cellssolar spectrumEgPoor absorption just below bandgap
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Possible solution: light trappingincreased absorption in SifsubsfsubsGoal:Ultra-thin-filmsolar cellKylie CatchpoleAlbedoAg
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H. Atwater (CALTECH)Quantum defect problem
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Semiconductor nanocrystals / quantum dotsMany open fundamental questions regarding multiple-exciton generation
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Quantum dot tandem solar cell (science fiction!)Plasmonic quantum dot solar cell
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Upconversion from infrared to visibleexc = 1490 nm10 mEwold Verhagen, Kobus Kuipers transmissionNano Lett. 7, 334 (2007) 550 nmexc = 1480 nmGuiding and concentration observed to /16Plasmonic hot-spot
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Plasmonic nano-solar cell (science fiction!) Small active semiconductor volume = low cost Small size low minority carrier lifetime requiredpn
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The Energy Problem:Needed: Large Area Cost-Effective Photovoltaics
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New third-generation solar cell conceptsYOU CAN HELP MAKE IT WORK !!