26 November 2019

At spin-off company Epishine, the printing presses are running and feeding out solar cells in printed electronics intended for indoor use. Olle Inganäs, professor emeritus and company founder, has an even higher goal: organic solar cells will contribute to solving the world’s energy problems.

Metre after metre of thin solar cells rolls out from the printing press Metre after metre of thin solar cells rolls out from the printing press THOR BALKHED

Metre after metre of thin plastic film rolls out from the coating machine at Epishine, located in the Ebbepark business park in Linköping. The machine gives the plastic a thin coating (100 nanometres) of light-sensitive material, in which the light photons are converted to charge carriers. Lamination is the next stage in the manufacture, to give small, flexible and transparent modules that are, despite their size, robust.

The light-sensitive layer has been carefully optimised to react to the light from indoor lamps. The layer harvests this light and converts it to electricity. We’re not talking about high voltages here, just a few volts, but it’s enough to power many of the small gadgets we have in the home, and that we are expected to an increasing degree to want to have online.
The solar modules will be commercially available in a year’s time.

Close to research

“All that remains is to use machines for the complete production line. We get higher quality from the machines: manual processing affects the quality of the solar cell modules”, Anders Elfwing, Epishine and LiUAnders Elfwing with a roll of solar cells Photo Thor Balkhedsays Anders Elfwing, supply chain manager at Epishine, who still retains one foot in the academic camp at LiU.

The company has 16 employees, half of whom have a background in research, many of them LiU alumni.

“Keeping close to research means that development proceeds at a high pace. As soon as we meet a problem, we can quickly go back to research to solve it”, says Anders Elfwing.

One important requirement for the raw materials is reproducibility: we must have a reliable commercial supplier. This is particularly true for the various mixtures of organic compounds. Further, even though only very small amounts are needed, work is in progress to ensure that the small solar cell modules can be recycled.

Professor emeritus Olle Inganäs is one of the founders of Epishine. He has devoted 30 years of his life to organic solar cells, or as he himself expresses it: “to what I find most interesting – solving the world’s energy problems”.

Major societal issue

Even when he started, 30 years ago, the energy crisis was one of the major societal issues.
“But during the 1990s, it was considered to be on the brink of stupidity to work on energy issues”, he remembers.
But Olle Inganäs has never been one to follow current trends.

“It’s dangerous if everyone follows individual strong voices: much more intellectual work than this is needed in order to make progress”, he says.

A research grant from the Knut and Alice Wallenberg Foundation is currently behind work to demonstrate that the technology works when scaled up. At the same time, development of solar cell technology is continuing.

Olle Inganäs, Professor emeritusOlle Inganäs, Professor emeritus Photo credit THOR BALKHED“When Mats Andersson at Chalmers University of Technology and I received funding from the Swedish Energy Agency in 2012-2013, the efficiency of the organic solar cells had reached 10%. Since then, it has increased by one percentage point per year, and is now at 17%”, says Olle Inganäs.

One of the reasons for the rapid development is the insight that an efficient solar cell must also function well as a light-emitting diode, and this insight swung the research into a new direction.

“We had to rewrite the rules for how a solar cell is to be constructed, since we had incorporated an energy sink. But it turned out to be perfectly possible to do the opposite, and today the creativity in the research labs in China is reaching new heights. We will reach an efficiency of 20% in just a few years.”

A variety of colours and shapes

The ultimate goal for Olle Inganäs, however, is not primarily to develop electricity supplies for lots of small gadgets: this is just a nice secondary effect. His goal is to make a serious contribution to solving the world’s energy problems. The European solar cell industry is currently facing hard times, even though demand is rising rapidly, and with it the amount of power generation that has been installed. Competition from China is fierce, and European strategy has been to concentrate on design.

“A lot of work is currently under way to reduce the power developed by silicon-based solar cells. They must become aesthetically more attractive, and this means that they are less efficient. Consumers want nice looking solar cells”, he says.

This means that the organic solar cells have suddenly gained a competitive advantage, because even if the efficiency is still somewhat lower than it is for silicon-based solar cells, it is easy to manufacture organic solar cells in a wide variety of colours and shapes.

“What is needed is a collected and common investment into brains and knowledge – a Manhattan project for peace. But if we could get the same budget for research into organic solar cells as the motor industry has for marketing cars in southern Italy, we would be able to make major progress into solving the world’s energy problems”, Olle Inganäs assures us.

Translated by George Farrants


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