Researchers solve a scientific puzzle that could improve the efficiency of solar panels

A Ph.D. from Loughborough University The student helped shed light on a solar panel puzzle that could help develop more effective devices.

Most of the solar energy in the world is currently produced by solar panels – also called photovoltaic panels – made of silicon.

Recently, new solar panels have been created from a semiconductor material called cadmium telluride (CdTe).

CdTe panels have been found to produce electricity at lower costs than silicon panels, and the addition of an element called cadmium telluride selenium has improved efficiency.

As a result, electricity generated by CdTe solar plants is produced at a lower cost than fossil fuels, which has economic and environmental benefits worldwide.

Until now, it was not clear why selenium increased efficiency, but thanks to Tom Fiducia, Ph.D. Student Researcher at the Center for Renewable Energy Systems Technology (CREST) And from an international team of researchers, the puzzle has been solved.

Tom has worked with solar energy experts from CREST, the University of Durham, Oxford University and Colorado State University in the United States to study the effect of selenium on solar panels. The results of the group were published in Nature Energy – a monthly peer-reviewed scientific journal presenting only the main research on energy in the natural and social sciences.

Their article, titled "Understanding the Role of Selenium in Passivation of Defects for Highly Effective Selenium-Dried Cadmium Alloy Solar Cells", revealed that selenium acts by overcoming the effect of harmful defects, at the same time. Atomic scale, CdTe panels.

This explains the increase in efficiency since electrons (subatomic particles carrying electricity), which are generated when sunlight hits the solar panel, are less likely to be trapped and lost. at the level of defects. This increases the amount of power extracted.

Tom, the lead author of the article, explains that the team discovered this "unexpected" behavior by measuring the amount of light emitted by panels containing selenium.

Since selenium is not uniformly distributed over the panels, they compared the "luminescence" emitted by areas where selenium was relatively absent or absent and areas where selenium was highly concentrated.

Tom explained, "Although it sounds counterintuitive, a good defect-free solar cell material is very effective at emitting light, and therefore highly luminescent.

"We mapped the luminescence emitted by a solar cell containing selenium at a resolution of about 1/10 000 to the millimeter and compared it to a similar high-resolution map of the selenium concentration taken exactly at the same surface of the cell.

"It is striking that data indicating that selenium-rich regions are luminescent are much brighter than pure cadmium telluride and that the effect is remarkably potent."

Tom hopes the results will lead to better solar panels and increased use around the world.

He commented: "Now that the improvement in selenium-induced efficiency is better understood, it may be possible to use this knowledge to further increase the efficiency of solar panels. in cadmium telluride.

For example, this could be simply by increasing the amount of selenium in the devices or by modifying its distributions in the cell.

"If efficiency can be improved, it will further reduce electricity prices and have a direct positive impact on regions that adopt the technology."

To appear in Nature Energyhe says, "It's good to be reassured that your work is moving in the right direction.

"I hope the results will be useful to other researchers and ultimately have a positive impact."

Professor Michael Walls, professor of photovoltaics and university supervising Tom's doctorate According to research, "we now know how selenium improves the efficiency of solar cells, it should be possible to further improve the power output .

"This is an excellent example of an international team that collaborates and brings its expertise and facilities and develops a fundamental understanding of the actual operation of the devices."