Carbon nanotubes could up organic solar cells' efficiency

Organic photovoltaics (PV) potentially promise cheap, lightweight devices, albeit at lower conversion efficiencies than crystalline materials such as silicon.

‘Everything is about efficiency versus cost — which method gives a little bit of headroom over the other,’ said Prof Ravi Silva, who heads Surrey University’s Advanced Technology Institute, where the latest work was performed.

Nevertheless, this balance has yet to properly favour the large-scale commercial uptake of organic PV, as Silva explained to The Engineer.

‘For the last 10 or 15 years lots of people have been working on organic materials, but the key breakthrough hasn’t come in yet — that is to achieve efficiencies as high as eight or 10 per cent.’

Some research groups have therefore looked at developing hybrid PVs that include semiconductor nanoparticles such as zinc oxide and tin oxide to overcome the low charge mobility in traditional organic materials.

‘We have so much knowledge in the area of inorganic materials, why not use the best properties of the inorganic materials to improve on the organics without compromising the ability to apply this over large areas in solution-processable routes?’ said Silva.