GLOBAL CHALLENGES

Nano Breakthrough for Solar Energy

Rebecca Kutzer-Rice | Date: 06-24-10 | Comments

Scientists from the University of Minnesota have developed a method of using nanotechnology that could lead to highly efficient solar cells in the near future.

In the wake of the BP oil spill, perfecting green and renewable energies seems more important than ever. Recognizing this urgency, researchers at the University of Minnesota (UM) have made an important breakthrough that could lead to more efficient solar energy.

Traditional, low-efficiency solar cells could become obsolete if research from the University of Minnesota is successful.

Current solar cells are largely inefficient. In the standard model, sun rays strike the top semiconductor layer of the cell�usually made out of silicon�where many electrons are absorbed before they can be harnessed. This absorption means that most of today's solar cells are only about 12 percent efficient. Low efficiency is a major reason why solar energy has not become mainstream.

In the past, scientists have tried to circumvent this problem by quickly transferring the electrons from the semiconductor to a wire before they can cool off. These efforts, however, have failed.

The UM researchers have taken a new approach to conserving the energy-rich solar electrons. By using quantum dots to construct the semiconductor layer on the nano-scale, the scientists were able to change the absorption properties of the solar cell. By switching from silicon to lead selenide, the researchers had even more success. Nano-scale semiconductors caused energy to be lost much more slowly. This delay allowed the scientists to relocate the energy into tiny wires made from titanium dioxide.

"This is a very promising result," says William Tisdale, one of the main researchers, according to a UM press release. "We've shown that you can pull hot electrons out very quickly�before they lose their energy. This is exciting fundamental science."

Although the titanium dioxide wires also eventually lose energy�a setback that will have to be solved before this technology can be implemented�the scientists have made a major step toward high-efficiency solar cells. Eray Aydil, another researcher from the project, predicts that quantum-dot solar cells could produce an efficiency of up to 65 percent�more than five times the efficiency of current cells.

"I'm comfortable saying that electricity from solar cells is going to be a large fraction of our energy supply in the future," Aydil states.

The research was funded by the U.S. Department of Energy and the National Science Foundation. Other researchers included Brooke Timp and David Norris from the University of Minnesota, and Xiaoyang Zhu and Kenrick Williams from the University of Texas-Austin.

Here at Smarter Technology, we recently reported a different method of using nanotechnology to improve solar cells. Would more efficient solar cells make you more likely to invest in alternative energies? Let us know in the comments section below!