Light trapping innovation lifts solar cell efficiency to 45 percent

December 03, 2015 // By Paul Buckley
Florida State University (FSU) researchers claim they are a step closer to making solar cells more effective at trapping and using light.

In a paper published in the Journal of Physical Chemistry Letters, Assistant Professor of Chemistry and Biochemistry Kenneth Hanson and his team have introduced a new strategy for generating more efficient solar cells. The team is composed of post-doctoral researcher Tanmay Banerjee and graduate students Sean Hill and Tristan Dilbeck.

Using the FSU process in an optimized solar cell the researchers claim they can increase the maximum efficiency from 33 percent to more than 45 percent.

“We’re looking not only for new materials but also new light harvesting processes to make solar cells better,” explained Hanson.

Though solar cells have grown in popularity, they are still not widely used by the general public as an energy source due to their high cost and low efficiency. A typical solar cell, at maximum, converts less than 33 percent of light into electricity, so researchers have been working to find ways to surpass this limit and make cells more efficient.

In the past, scientists have put an extra photon upconversion filter before or after the cell to catch the low energy, unused light and convert it into usable, high-energy light. But, Hanson wanted to integrate the process directly into the cell.

The researchers were able to do that by using self-assembly. Through a soaking procedure, the researchers assembled two molecules, an acceptor and sensitizer, on a surface. Once assembled, the molecules work in concert to perform photon upconverion, combining two low energy, green photons to generate a higher energy, blue photon, which can then be used to generate electricity.

“It is definitely a stepping stone toward making more efficient solar cells,” Hanson said. “Our current work demonstrates a feasible method.”

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