Imagine a day when a skyscrapers’ windows are tinted with thin-film solar cells that reduce heat entering the building while generating electricity.
And imagine greenhouses that are covered with the same types of solar cells that both admit light needed for plant growth and simultaneously produce electrical energy from the sun.
Chemistry professor Neal Armstrong says those concepts are being developed and demonstrated today, and systems should be commercially available well within 10 years.
The Armstrong research program has been focused on the basic science that underpins the development of these new solar-cell technologies for the last 25 years, starting with closely related light-emitting technologies — organic light-emitting diodes, which are already in widespread commercial use.
Armstrong’s chemistry and materials science collaborators include R. Clayton Shallcross, Erin Ratcliff, Oliver Monti, S. Scott Saavedra, Jeanne Pemberton and Dominic McGrath.
The time to get new solar-energy conversion technology on the market is now, he says, as interest in solar energy as a competitive source of electricity grows, driven in large part by the decreasing cost of electricity from solar cells.
Startup companies in the solar-power industry have now produced new, lightweight and flexible, and increasingly higher-efficiency materials that may one day be available on the shelves of home-improvement stores.
“There is a lot of thin-film technology coming along,” Armstrong says. “Making a solar cell that can absorb light from the sun and efficiently turn it into electricity is well-established.
“What’s challenging is creating solar cells using ‘printing’ technologies, especially when it comes to putting the electrical contacts on that material.”
It’s a chemistry challenge. Today’s electrical contacts on conventional solar cells are typically made of silver, copper or aluminum, conductive materials. Those materials are not easily compatible with the interlayers of newer, “printable” solar cells.
What is needed instead are thin “oxide” films that are both transparent and electrically conductive, but may also be chemically reactive toward the light-absorbing “active” layers in these new solar cells.
Understanding and controlling that chemical reactivity in printing processes to create up to a kilometer per day of one-meter wide, flexible and semi-transparent solar cells is the primary focus of the basic science that will determine how rapidly these technologies come to market, he says.
Armstrong says he and his team have filed a patent disclosure for a specially modified oxide electrical contact that will successfully interface with many of these new thin-film solar cells.
“We have to start thinking about putting solar cells everywhere you can imagine if we are to meet the energy demands of the 21st century and lower our overall carbon footprint. It’s going to happen, it’s just a question of when.”