Left) Photographs under UV light of quantum dots with different ratios of selenium to sulfur, resulting in different colors. (Right) Illustration of the quantum dot layers absorbing different wavelengths of light as the photoanode in a solar cell. Credit: Santra, et al. ©2013 American Chemical Society

Synergistic effect discovered in layered quantum dot solar cells

January 10, 2013 by Lisa Zyga

(Phys.org)—Scientists have discovered that a solar cell consisting of two or three layers of quantum dots, with each layer tuned to a different part of the solar spectrum, has an efficiency that is 40-60% higher than the sum of the efficiencies of separate solar cells each made of one of the individual layers. The synergistic effect of the layered architecture could lead to new ways of designing quantum dot solar cells with high efficiencies and broad-spectrum absorption.

The researchers who designed and fabricated the new solar cells, Pralay K. Santra and Professor Prashant V. Kamat at the University of Notre Dame in Indiana, wanted to test the previously proposed concept of a rainbow solar cell, which can harvest photons of all “colors” or wavelengths of the visible spectrum.

In order to fabricate a rainbow solar cell, scientists need to incorporate light-harvesting components with various properties to capture different parts of the spectrum. One way to do this is by using quantum dots, which can be tuned to capture specific wavelengths of light. The typical way of tuning a quantum dot’s band gap to capture a particular wavelength of light is to control the dot’s size during synthesis.

Read more: Synergistic effect discovered in layered quantum dot solar cells — phys.org.

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