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 Laser sensor LAH-G1 - optical distance sensors with measurement value display
15.08.2017 | WayCon Positionsmesstechnik GmbH

nachricht Engineers find better way to detect nanoparticles
14.08.2017 | Washington University in St. Louis

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>