In the current work, Tisdale and his colleagues demonstrated that quantum dotsmade not of silicon but of another semiconductor called lead selenide -- could indeed be made to surrender their "hot" electrons before they cooled. The electrons were pulled away by titanium dioxide, another common inexpensive and abundant semiconductor material that behaves like a wire.
"This is a very promising result," said Tisdale. "We've shown that you can pull hot electrons out very quickly before they lose their energy. This is exciting fundamental science."
The work shows that the potential for building solar cells with efficiencies approaching 66 percent exists, according to Aydil.
"This work is a necessary but not sufficient step for building very high-efficiency solar cells," he said. "It provides a motivation for researchers to work on quantum dots and solar cells based on quantum dots."
The next step is to construct solar cells with quantum dots and study them. But one big problem still remains: "Hot" electrons also lose their energy in titanium dioxide. New solar cell designs will be needed to eliminate this loss, the researchers said.
Still, "I'm comfortable saying that electricity from solar cells is going to be a large fraction of our energy supply in the future," Aydil noted.
|Contact: Preston Smith|
University of Minnesota