Highly efficient solar cells from quantum dots

The 22 August 2010 edition of Texas Science reports on research by chemist Xiaoyang Zhu at The University of Texas at Austin suggesting that conventional solar cell efficiency could be more than doubled, from the current limit of 30% to more than 60% using semiconductor nanocrystals, or quantum dots to capture the energy from "hot electrons."

The maximum efficiency of the silicon solar cell in use today is about 31 percent. That’s because much of the energy from sunlight hitting a solar cell is too high to be turned into usable electricity. That energy, in the form of so-called “hot electrons,” is lost as heat.
If the higher energy sunlight, or more specifically the hot electrons, could be captured, solar-to-electric power conversion efficiency could be increased theoretically to as high as 66 percent.

 “If we take the hot electrons out, we can do work with them,” says Zhu. “The demonstration of this hot electron transfer establishes that a highly efficient hot carrier solar cell is not just a theoretical concept, but an experimental possibility.”