New measurement techniques reveal that selenium, a simple elemental semiconductor, could deliver better solar performance than previously thought — especially if its micro-level defects can be better controlled.
Selenium might not be the first element that comes to mind when thinking of solar power — but that may be about to change. A groundbreaking study from the Technical University of Denmark [12.6°E, 55.8°N] has shone a new light on selenium’s hidden potential, offering fresh hope for low-cost, high-performance solar cells.
Why Selenium?
Selenium is air-stable, strongly absorbs visible light, and can be manufactured into solar thin films at relatively low cost. Despite this, its use in solar tech has been limited by incomplete understanding of how its charge carriers (electrons and holes) behave — particularly under real-world conditions like sunlight and heat.
The new Danish study has changed that. Using a clever diagnostic tool called the carrier-resolved photo-Hall effect, researchers measured how both electrons and holes move and interact under varying light and temperature conditions. This method, still relatively new in materials science, allowed the team to pinpoint the true electrical behaviour of selenium films without the guesswork.
What Did They Find?
It turns out previous measurements may have underestimated selenium’s potential. Under simulated sunlight, carrier mobility (a key factor in solar cell efficiency) is significantly higher than expected. The study shows electron and hole mobility increasing with light intensity — suggesting that under normal sunlight, these films could perform much better than lab estimates had indicated.
Moreover, while early measurements suggested long carrier lifetimes (which is usually good), those were likely skewed by surface defects. The team found that in the real operational state of a solar cell, the charge carriers live shorter lives but move more efficiently than assumed. This insight could reshape how we design and optimise selenium-based solar cells.
The Key Challenge: Defects
The study didn’t just reveal good news. It also pinpointed why selenium solar cells haven’t yet reached higher efficiencies: defects at the surface and grain boundaries are causing premature recombination of charges — essentially wasting some of the energy generated. But now that researchers know exactly where the problem lies, it becomes a matter of engineering solutions, like better surface passivation or improved crystal growth techniques.
A Promising Future for Thin-Film Tech
With improvements in fabrication and defect management, the researchers estimate that selenium could support more efficient, thinner solar cells — and potentially play a leading role in tandem cell architectures, where it acts as a high-voltage top layer.
This makes selenium not just a historical curiosity (it was used in the world’s first photovoltaic devices), but a genuine contender in the next generation of solar innovation.
As this Danish study shows, sometimes all it takes is a smarter way to look at old materials to unlock entirely new potential.
Source
Variable-temperature and carrier-resolved photo-Hall measurements of high-performance selenium thin-film solar cells, APS Physical Review Journals, 2025-04-03
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