Solar cells deliver world-record performance

Vice-Chancellor Anders Hagfeldt, Professor of Physical Chemistry, has now published a new study on solar cell research in the scientific journal Nature.

What is your study about?
“It’s a high point from the old days, my research period. It’s a really exciting project about a solar-cell technology that’s the hottest topic in research in the area right now – perovskite solar cells, as they’re called.”

What was the outcome?
“In terms of efficiency, we achieved a world record. We found a molecule that removes defects on the surface of the perovskite material, so we get a performance in the material that was close to the theoretically best possible. In the lab, we’ve now reached 25.6 per cent efficiency. The certified world record is 25.5 per cent.”

What about sustainability?
“In general, the efficiency of perovskite solar cells in a lab environment can be said to be as good as that of the conventional silicon solar cells available on the market today. In this study, we’ve been doing long-term tests in which we expose the solar cells to sunlight for 500 hours, and the stability looks very good. We don’t lose much in terms of efficiency. The question is whether this will be maintained when they’re tested out of doors, in real-life conditions, over many years. I think that’s the main question to answer ahead of industrial production. But it looks promising.”

How significant could your findings be?
“They’ll have an impact throughout the research world. We had an article on the same theme published in Science last autumn, in which we introduced a concept for producing the perovskite material with an ideal composition. And there’s another side of this that’s exciting: if you have a very high-quality semiconductor in the perovskite material, the solar cells can work extremely well as light-emitting diodes (LEDs) if they’re run backwards – that is, if you send current in instead of out. There, we’ve got the world record for luminosity of perovskite solar cells.”

Do you have any more scientific articles under way?
“We’re doing a follow-up study in which we have world-record listings at large-scale units. From the single solar cells we use in the lab, we’ve moved on to modules of 30–60 square centimetres in size. In those, the efficiency is around 21 per cent.”

How does it feel, leaving behind this exciting research that’s been such a big part of your life?
“For my own part, being Vice-Chancellor is a new and tremendously exciting chapter. As for the research, I feel satisfied and it’s great to finish on a high like this, with two world records. It feels good to be able to keep up in a modest way.”

Does that mean you’re going to do a bit of research on the quiet?
“Yes, you could say that. I still have a couple of postdocs who formally belong to my research group and are now coming here to the Ångström Lab, where they’ll be doing research with my colleagues. I can drop in at Ångström sometime and see how it’s going.”

So you’re going to collaborate with the solar-cell researchers at the University?
“Yes, as far as I can stay involved, through coaching and by sharing my experience from Switzerland.”