Portrait: The athlete in the lab coat

At the Helmholtz Innovation Lab HySPRINT, Steve Albrecht finds the appropriate techniques to produce the world's most efficient perovskite solar cells.

At the Helmholtz Innovation Lab HySPRINT, Steve Albrecht finds the appropriate techniques to produce the world's most efficient perovskite solar cells. © HZB/M. Setzpfand

Video clip: How do perovskite solar cells works? © HZB

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Steve Albrecht is researching on perovskite solar cells and holds several efficiency world records with his team. Back in his schooldays, he was going to become either a competitive gymnast or a scientist. He chose science, but the same athletic ambition still drives his research forward.

Renovation workers are at his house, and the old water damage is finally being repaired. Steve Albrecht dashes around between the bathroom, the ringing phone and his desk, and soon has to leave for his office, but is not hectic about it: if anyone is used to juggling many things at once, it’s him. At 35 years old, he is already a junior professor at TU Berlin and has his own junior group at HZB, a considerable sporting career, and also a twelve-year-old son and a nine-year-old daughter. “The renovators are here a lot these days to fix the water damage,” he says with a shrug, “but hopefully the whole thing will be done soon.”

Steve Albrecht lives with his family in Werder, not far from Potsdam, where he grew up. But he is always out and about: sometimes at TU Charlottenburg, but mostly at HZB in Adlershof with his workgroup. “Recently, I wished for a solar-powered charging station for electric cars here in Adlershof,” he says with a smile. He addressed this request to the Governing Mayor Michael Müller, who had just given Albrecht the renowned Berliner Wissenschaftspreis in the young researcher category, and Albrecht had been asked to express a wish to politicians on the open stage. “We’ll see if something comes of it.” Whether it was his wish that was heard or not, there are definitely going to be four charging stations built at HZB this spring. This is fitting because, firstly, Steve Albrecht can then finally drive to work in an electric car and, secondly, as a solar researcher, he is of course predestined to be using solar energy.

Efficiency records of tandem solar cells

Behind his lab doors in Adlershof, he and the colleagues from his group are working to make solar cells more and more efficient. In fact, he is even the double world record holder in this respect. “Every six months, the journal Progress in Photovoltaics publishes efficiency tables in which the latest values from all the researchers around the world are published,” he relates. Currently, the highest efficiency reached by solar cells made from a combination of perovskite and CIGS semiconductors (which stands for copper, indium, gallium and selenium) is 23.3 percent. Perovskite and CIGS each capture a different spectral range of sunlight, which is why the yield is particularly high. Using solar cells combining perovskite and conventional silicon, the highest efficiency achieved by Albrecht’s workgroup is currently 29.15 percent. Again, that is a new record and was recently added to the American National Renewable Energy Laboratory’s record list. This is a kind of ‘wall of fame’ that has been maintained since 1976 – “it was always my dream to have my name on that list one day,” says Steve Albrecht.

But world record or no world record, “the thing that drives you in this race is the same as in sports,” he says. “When someone sets a goal to run a marathon in under three hours, spends a long time training time for it, and finally completes it in 2 hours and 50 minutes, it is incredibly satisfying. That’s how it is for us.” The medium-term goal of Steve Albrecht and his colleagues is to break the 30 percent barrier – which would take them into an area that theorists have already predicted by calculations to be technically feasible.

Many factors determine whether a solar cell composition becomes the big success

As much a driving force as his sporting ambition has always been the creative nature of his job: Steve Albrecht would regularly lock himself up in the laboratory, surrounded by every conceivable chemical, and get tinkering. He would stir solutions, trigger chemical reactions, and finally, using a pipette, build up around 15 sandwiched layers of different materials until he had a monolithic plate – indeed a solar cell. He used to do this himself, but now his team does it for him. A number of factors, including the optoelectronic quality of the result, determine whether or not this tinkering becomes a great success. “You're as happy as a child when you measure the performance of the new solar cell for the first time,” Albrecht says. “We do our measurements under solar simulators – or in other words under an artificial sun – and in 90 percent of cases the results are sobering.” But, the other ten percent of cases, which represent sometimes minor and sometimes major advancements, make up for all the failed experiments.

And all sporting ambition aside, the work really gets going once a new world record has been set. Then comes the stage when the researchers have to transfer the successful formula from a chip the size of a fingernail to large panels that could be used in practical applications – and they have to make sure these will last for up to 25 years so that they can be placed on the market. These are long-term stages in the development, for which Albrecht is collaborating with other colleagues inside and outside HZB in the scope of the Helmholtz Innovation Lab HySPRINT.

Perovskite solar research is a field with gold-rush atmosphere 

The field of future solar cell research is currently abuzz with a gold-rush atmosphere. The most promising material of all is semi-organic metal halide perovskite – the compound with which Steve Albrecht is now working. “Its semiconducting properties were already described in the 1970s,” he explains, “but for many decades, nobody did any research on its application in solar cells.” Scientists at the time thought there was not enough hope in it – and were greatly mistaken. “Even when I first started working on it, in around 2012, perovskite was still being ridiculed,” he recalls. Back then, they were only achieving efficiencies of around ten percent, when their efficiency suddenly took off and kept rocketing higher. It was in this atmosphere of optimism that Steve Albrecht began his scientific career.

An unusual hobby

It was by no means certain that he would ever study physics: already at primary school, he was one of the most promising gymnasts in the Brandenburg area. On many days, he had gym even before school started. Instead of attending one of the sporting gymnasiums in Cottbus or Berlin, however, he finally decided to attend a science gymnasium. Nevertheless, the tricks and training from his athletic days are still useful today, at least for his hobby: he works as a stuntman in film productions and has even appeared in front of the camera in Babelsberg for Hollywood. One of his favourite stunt scenes is when, instead of the actor, he threw himself out of a window of an interrogation room and plummeted to the ground, tied to a wooden chair. Steve Albrecht laughs to think about it. Yes, even today he would still jump at another offer for a stuntman position – “except for the really dangerous things; I definitely don't do those anymore!” He will not take any unnecessary risks because of his family, of course, but also so as not to jeopardize his great sporting goal as a researcher: to break the 30 percent mark in the efficiency of solar cells.


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Autor: Kilian Kirchgessner