Researchers at the University of California, Los Angeles have developed a new type of polymer solar cell which lets through 66% of light at a wavelength of 550 nanometres (which is green) and about 60% for the rest of visible spectrum.

Previously, transparent solar cells have been made by adding a coating to windows which traps light inside and directs it to photovoltaic cells at the edge of the pane.

The new type of solar cells are made of a photovoltaic plastic which converts infrared light to electricity. It is manufactured by "solution processing" which allows the cells to be manufactured on a large scale using "roll-to-roll" manufacturing techniques – much the same way newspapers are printed on paper.

In this process, an electrode is built by spraying a network of silver nanowires onto a layer of titanium dioxide, then filing in the gaps with nanoparticles of indium tin oxide.

As well as potential applications on windows and screens, polymer solar cells like these have the potential to be mass produced more cheaply than traditional silicon photovoltaic cells. However, the efficiency record for turning light into electricity currently stands at 40% for silicon-based cells, while the record for polymer solar cellss is just 10.4%. Trade-offs for transparency, bring the new solar cells efficiency down to about 4%.