Nanocrystal Conductance Enhanced by Gold Solution
Nanocrystal development has a very promising future thanks to the latest research into gold solution. The future of solar energy made from nanocrystals in order to produce clean and renewable energy from liquid transport fuels is bright. Researchers working at the U.S. Department of Energy of Lawrence Berkely National Laboratory has recently reported a new technique that increases the electrical conductivity of nanorod crystals aka nanocrystals of cadmium selenide which increases 1000,000 times. Read more about Nanotechnology in the Energy Industry: Applications and Market Potential
The demand for the world’s energy has more than doubled in the past few decades and is said to double by 2050. By the 21st century the world’s energy demand is said to triple. The power hungry world needs an alternative form of renewable energy in order to survive. This is where the latest nanocrystals come in. Solutions such as these can help us use sunlight to generate electricity as well as use it to split water molecules which will help in the production of fuels as an ideal energy source envisioned by scientists. Nanocrystals can play a pivotal role to make this vision a reality. Electrical conductance in nanocrystals is an important element in both solar fuel technologies as well as solar electricity generation.
Research has shown that while treating the nanocrystals with chemicals like etching the surface has shown to enhance the conductivity of these thin film nanocrystals, its actually also altering the electrical properties of the semiconductor. So for instance when the material from an n-type semi conductor is switched to a p-type it’s actually altering the density of the surface states. Also many previous studies didn’t show why the conductance was enhanced other than showing that the surfactant was removed.
The latest study by Sheldon, Alivisatos as well as their co-authors involved single nanostructure electrical measurements in order to make systematic comparisons between both cadmium-selenide nanocrystal both with and without gold tips. The tipping process commenced with the addition of gold salt to the solution containing cadmium-selenide nanocrystal and toluene. The result of which was that the gold metal was selectively deposited on the tips of the nanorods.
Later a silicon water test was also dipped in this nanocrystal solution. After it was submerged the evaporation of the toluene began and individual cadmium-selenide nanocrystal was deposited across a pre-defined surface of gold electrodes which was then fabricated via electron beam lithography. The result of this experiment was gold-tipped cadium-selenide heterostructure devices whose electrical properties i.e. conductance was shown as a two terminal geometry function of temperature and source drain voltage.
The next step for nanocrystal technology will be to determine if the improvements in the electrical behavior can also translate into improved energy production based on nanocrystals. Initially the research group will investigate the use of the solution grown contact in various photovoltaic applications. This is one of the biggest steps for nanocrystals based power generation and the results look promising even though a useable product is at least five years away. The research was mainly funded by DOE Office of Science via the Berkely Lab’s Helios Solar Energy Research Center.
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