Physorg.com is reporting that University of Notre Dame researchers have created solar cells from different sized quantum dots, with each dot tuned to a specific wavelength of light. By arranging this quantum dots in an orderly pattern, the researchers hope they can make “rainbow” solar cells, which can then harvest a much greater range of frequencies of sunlight. Quantum dots exhibit something called the “size quantization effect.” Different sized quantum dots absorb different light frequencies – smaller dots absorb shorter wavelengths, and larger dots absorb longer wavelengths. By combining the different sized dots on one solar cell, they can create cells that absorb much more light and are much more efficient.
Electron transport through a structure of nanoparticles (left) and more ordered nanotubes (center) is shown. At right, different wavelengths of light can be absorbed by different-sized quantum dots layered in a rainbow solar cell. Image credit: Kongkanand, et al. ©2008 ACS.