|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.
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.