Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Titania nanotubes create potentially efficient solar cells

09.02.2006


A solar cell, made of titania nanotubes and natural dye, may be the answer to making solar electricity production cost-effective, according to a Penn State researcher.



"Solar cell technology has not changed very much over time and is still predominantly silicon solar cells," says Dr. Craig Grimes, professor of electrical engineering and materials science and engineering. "It takes a great deal of energy, 5 gigajoules per square meter, to make silicon solar cells. It can be argued that silicon solar cells never fully recover the energy it takes to make them in the first place."

The new focus in solar cells is toward dye sensitive solar cells, which have been made using nanoparticles and a variety of dyes.


"Nanoparticle solar cells are the gold standard of this new approach," says Grimes. "However, because of limitations, it appears they have gotten as good as they are going to get."

The researchers are instead looking at titania nanotubes to replace the particulate coatings in dye sensitive solar cells and, their initial attempt produced about 3 percent conversion of solar energy to electricity, they report in today’s issue of Nano Letters. The researcher’s inability to grow longer titania nanotubes, constrained the solar conversion rate.

"I think we can reach a 15 percent conversion rate with these cells, and other researchers do as well," says Grimes. "That is 15 percent with a relatively easy fabrication system that is commercially viable."

Conventional solar cells are made from blocks of slowly made silicon boules that are sliced into wafers. Grimes and his team use an easier approach. They coat a piece of glass with a fluorine-doped tin oxide and then sputter on a layer of titanium. The researchers can currently lay down a 500-nanometer thick titanium layer. They then anodize the layer by placing it in an acidic bath with a mild electric current and titanium dioxide nanotube arrays grow to about 360 nanometers. The tubes are then heated in oxygen so that they crystalize. The process turns the opaque coating of titanium into a transparent coating of nanotubes.

This nanotube array is then coated in a commercially available dye. The dye-coated nanotubes make up the negative electrode and a positive electrode seals the cell which contains an iodized electrolyte. When sun shines through the glass, the energy falls on the dye molecules and an electron is freed. If this electron and others make their way out of the tube to the negative electrode, a current flows. Many electrons do not and are recombined, but the tube structure of the titanium dioxide allows an order of magnitude more electrons to make it to the electrode than with particulate coatings.

"There is still a great deal of optimization of the design that needs to be done," says Grimes. "Now, with the help of the Pennsylvania Energy Development Authority, we will have equipment to make high quality titanium coatings that are thicker. If we get about 3 percent conversion with 360 nanometers, what we could get with 4 microns is an exciting question we soon hope to answer."

The thickness of the titanium layer constrains the height of the nanotubes. With thicker initial coatings, longer tubes would produce more electrons that do not recombine, producing more electricity.

Other aspects of the titania nanotube dye sensitive solar cells that need to be optimized include the thickness of the cells. Currently, spacers separate the two layers and provide internal support. These spacers are 25 microns thick. If the spacers could be made as sturdy, but shorter, there would be less of a distance for the electrons to travel and more electrons will make it across the electrodes.

A’ndrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Power and Electrical Engineering:

nachricht Energy hybrid: Battery meets super capacitor
01.12.2016 | Technische Universität Graz

nachricht Tailor-Made Membranes for the Environment
30.11.2016 | Forschungszentrum Jülich

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>