IMEC increases lifespan of solar cells

IMEC has developed a method of stabilising the nanomorphology of organic solar cells, increasing their life by 10 times.

With these stabilised solar cells, efficiencies were achieved comparable to state-of-the-art organic solar cells.

This paves the way to commercial organic solar cells with an operational lifetime of more than five years and efficiencies of more than 10 per cent.

The efficiency and operation of organic solar cells depends on the nanomorphology of the active layer, that is to say on a stable mix of organic compounds that can trap the light's energy and transport it to an electric contact.

IMEC has reported such cells based on P3HT:PCBM with efficiencies close to five per cent.

But to date, the lifetime of these cells has been too short for commercial applications, for which five years is regarded as a minimum length.

All solar cells based on an intimate mixing of organic semiconductors deteriorate when used long term.

This is caused by segregation of the mixture whereby the compounds tend to separate into different phases, reducing the efficient conversion of light into electricity.

This phase segregation is related to the mobility of the organic polymer and that fixation of the nanomorphology of the polymers could result in a prolonged operational lifetime.

IMEC has developed a method and conjugated polymers to stabilise the nanomorphology of the active layer, making it more robust to phase segregation under prolonged operation.

Experiments on bulk heterojunction organic solar cells based on this new material showed no degradation of the efficiency after more than 100 hours, whereas reference cells degraded after only a few hours.

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