The Ultimate Solar Cell?
The ultimate step in utilizing solar power is to convert maximum energy from sun into electricity. This will make solar power highly cost-advantageous compared to other traditional power sources. Capturing energy wasted as heat from the sun can increase solar conversion efficiency greatly. Research funded by the U.S. Department of Energy is on-going to make this happen.
Not all solar energy utilized:
Actually only about 31% of solar energy is converted into electricity. The rest of the energy is not able to be harnessed as it becomes heat – as ‘hot electrons’ – which is lost very quickly because electrons cool down very fast. Capturing almost all solar energy and converting to electricity is the goal of the ‘ultimate solar cell’.
Utilizing the hot electrons:
Since half the solar energy is lost as heat, the first step will be to slow down the cooling rate of these electrons. The second step will be to capture the hot electrons and use them before the heat energy gets dissipated and lost. And harness the heat energy taking the electrons out via a conducting wire with minimal energy loss.
Semiconductor nanocrystals – quantum dots:
Quantum dots play a pivotal role in the transfer of hot electrons. The research showed that the hot electrons can be transferred to a titanium dioxide electron conductor with the help of photo-excited lead selenide nanocrystals (quantum dots). The aim is to minimize energy loss by having the most effective conductor wire. This will allow the fast removal of electrons from the solar cell before they cool down.
Solar power – the best energy source:
With growing awareness of dwindling sources of fossil fuels, green, environmentally friendly, bio-renewable energy sources are beacon lights of energy sources in future. Solar energy will be the most efficient and common source of such energy. This research is an important step in the creation of the ultimate solar cell.
The team:
Chemist, Xiaoyang Zhu, University of Texas, Austin, led the team consisting of William Tisdale, Brooke Timp, David Norris and Eray Aydil – all from the University of Minneso and also Kenrick Williams, from University of Texas.
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July 2nd, 2010
This is certainly useful when electricity is what is needed. We have also seen attempts to increase the efficiency of photovoltaic cells by capturing the energy as heat in a kind of CHP array. Heat also has many potential options for energy storage that are not available for electrical storage.
July 14th, 2010
Yea, I tried to get on my asphalt shingle roof the other day but it was too hot. And I live in Montana, so this doesn’t even compare to someplace like Las Vegas or Pheonix. Don’t we have any low-budget roof blankets that would capture some of this wasted heat and convert it to something useful like charging a big battery?
August 3rd, 2010
Lead selenide would seem to be cheaper than gallium arsenide. Unfortunately with all these thermionic approaches, they give max efficiency at higher temps, which means concentrating systems. They don’t lend themselves to panels on the roof.
August 4th, 2010
Concentrated systems can also be constructed using lenses rather than reflectors. This would allow some higher temps. There is no replacement however to simply gathering more sunlight. Heliostats on the ground might be employed (albeit less efficiently) to increase sunlight to roof mounted panels.