Researchers from the University of Bristol have found a way to create new kinds of plastic semiconductors that can absorb light.

The new polymeric nanoscale semiconductors could be used for more flexible and more efficient solar cells and photodetectors as well as for splitting of water into hydrogen and oxygen for fuel.

Lightweight semiconducting plastics are now widely used in mass market electronic displays such those found in phones, tablets and flat screen televisions. However, using these materials to convert sunlight into electricity, to make solar cells, is far more complex.

Working with researchers at the University of Cambridge, , Dr Xu-Hui Jin and colleagues in the chemistry lab say this could be a “game changer” by allowing the energy from sunlight absorbed in these materials to be captured and used more efficiently.

Previously photons of light only moved 10nm in plastic semiconductors. The new work allows the photons to travel 200nm, all the way through a typical substrate. This makes a plastic solar cell more efficient.

“The gain in efficiency would actually be for two reasons: first, because the energetic particles travel further, they are easier to “harvest”, and second, we could now incorporate layers around 100 nanometres thick, which is the minimum thickness needed to absorb all the energy from light – the so-called optical absorption depth. Previously, in layers this thick, the particles were unable to travel far enough to reach the surfaces,” said Dr George Whittell from Bristol’s School of Chemistry.

The research team now plans to prepare structures thicker than those in the current study and greater than the optical absorption depth, with a view to building prototype solar cells based on this technology.

Nick Flaherty