Metal oxides hold the key to cheap, green energy

April 19, 2012
Metal oxides hold the key to cheap, green energy
Louis Piper, assistant professor of physics at Binghamton University, is harnessing the energy of sunlight by tuning the optical and electronic properties of metal oxides. Credit: Jonathan Cohen/Binghamton University

Harnessing the energy of sunlight can be as simple as tuning the optical and electronic properties of metal oxides at the atomic level by making an artificial crystal or super-lattice 'sandwich' says a Binghamton University researcher in a new study published in the journal Physical Review B.

"Metal oxides are cheap, abundant and 'green,'" said Louis Piper, assistant professor of physics at Binghamton University. "And as the study proved, quite versatile. With the right touch, metal oxides can be tailored to meet all sorts of needs, which is good news for technological applications, specifically in and flat screen displays."

Here's how it works: semiconductors are an important class of materials in between metals and . They are defined by the size of their band gap, which represents the energy required to excite an electron from the occupied shell to an unoccupied shell where it can conduct electricity. covers a range of 1 (infrared) to 3 (ultraviolet) electron volts. For transparent , a large band gap is required, whereas for , a band gap corresponding to green light is needed. Metal oxides provide a means of tailoring the band gap.

But while metal oxides are very good at electron conduction, they are very poor "hole" conductors. Holes refer to absence of electrons, and can conduct positive charge. To maximize their technologically potential, especially for artificial photosynthesis and invisible electronics, hole conducting metal oxides are required.

Knowing this, Piper has begun studying layered metal oxides systems, which can be combined to selectively 'dope' (replace a small number of one type of atom in the material), or 'tune' (control the size of the band gap). Recent work revealed that a super-lattice of two hole-conducting copper oxides could cover the entire . The goal is to improve the performance whilst using environmentally benign and cheap metal alternatives.

For instance, indium oxide is one of the most widely used oxides used in the production of coatings for flat screen displays and solar cells. It can conduct really well and is transparent. But it is also rare and very expensive. Piper's current research is aimed towards using much cheaper tin oxide layers to get electron and hole conduction with optical transparency.

But according to Piper, his research shows that one glove will not fit all purposes.

"It's going to be a case of some serious detective work," said Piper. "We're working in a world where physics and chemistry overlap. And we've reached the theoretical limit of our calculations and fundamental processes. Now we need to audit those calculations and see where we're missing things. I believe we will find those missing pieces by playing around with metal oxides."

By reinforcing metal oxides' 'good bits' and downplaying the rough spots, Piper is convinced that the development of new and exciting types of metal oxides that can be tailored for specific applications are well within our reach.

"We're talking battery storage, fuel cells, touch screen technology and all types of computer switches," said Piper. "We're in the middle of a very important gold rush and its very exciting to be part of that race to strike it rich. But first we have to figure out what we don't know before we can figure out what we do. One thing's for sure: hold the key. And I believe that we at Binghamton University can contribute to these efforts by doing good science and taking a morally conscious approach."

Explore further: Bacteria from the deep can clean up heavy metals

Related Stories

'Impossible' conductivity explained

May 19, 2010

(PhysOrg.com) -- Bring two materials that are not themselves conductive into contact and, exactly at their interface, something remarkable happens: at that precise point, conduction is possible.

Metal oxide simulations could help green technology

January 10, 2012

(PhysOrg.com) -- University of California, Davis, researchers have proposed a radical new way of thinking about the chemical reactions between water and metal oxides, the most common minerals on Earth. Their work appears ...

ORNL finding has materials scientists entering new territory

February 21, 2012

Solar cells, light emitting diodes, displays and other electronic devices could get a bump in performance because of a discovery at the Department of Energy's Oak Ridge National Laboratory that establishes new boundaries ...

Recommended for you

New nanomaterial maintains conductivity in 3-D

September 4, 2015

An international team of scientists has developed what may be the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in three dimensions.

Graphene made superconductive by doping with lithium atoms

September 2, 2015

(Phys.org)—A team of researchers from Germany and Canada has found a way to make graphene superconductive—by doping it with lithium atoms. In their paper they have uploaded to the preprint server arXiv, the team describes ...

Making nanowires from protein and DNA

September 3, 2015

The ability to custom design biological materials such as protein and DNA opens up technological possibilities that were unimaginable just a few decades ago. For example, synthetic structures made of DNA could one day be ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.