TSB award recognises screen-printed solar cells

A firm developing organic solar cells that can be printed onto glass to create power-generating windows has won £100,000 to commercialise its technology.

Oxford Photovoltaics (Oxford PV) topped the energy category of the Technology Strategy Board (TSB) Disruptive Solutions Competition with its solar glazing research, which harnesses the sun’s energy in a similar way to photosynthesis.

Other projects have looked separately at solar panels that mimic plants and technology for turning glass into generators, but the Oxford University spin-out has now combined the two ideas with a solid-state dye-sensitive cell.

Existing organic cells typically use a liquid dye that acts like chlorophyll, releasing electrons that are carried by a conductive, corrosive electrolyte solution to an external circuit. Oxford PV’s version uses a solid metal oxide electrode soaked in the organic dye, which means the cells can be screen printed onto a substrate.

‘One of the great advantages is that we can process it very easily,’ inventor and chief scientific officer Dr Henry Snaith told The Engineer. ‘You don’t have to worry about sealing and encapsulation, which is an issue for the electrolyte dye cell.’

Screen printing allows the cells to be easily sealed and protected against the environment, while using solid materials rather than corrosive liquid should increase the life of the technology.

‘One of the issues with organic cells has been that they have very low life expectancy – two or three years – and to get into the building integrated sector we need expectancies of 20 years or more,’ said chief executive Kevin Arthur.

The process tints the glass depending on the dye colour, with green preferred for its high efficiency in producing electricity and because human eyes are more sensitive to green light than many other colours, although red and purple also work well.

The company hopes to be able to apply the technique to other building materials such as sheet steel but has started with glass because of its high rates of efficiency and stability.

‘We think there’s an enormous market in building the solar-cell material into the fabric of the building rather than having bolt-on solar cells,’ said Arthur.

‘And the reason we’re using organic materials and screen printing is because the manufacturing costs are so much lower. We can probably be half the price of existing technologies that are dependent on rare earth metals and high vacuum processing.’

Oxford PV will use the TSB money to accelerate the development of high-quality prototypes by working with other manufacturers over the next six months.

A low-cost solar cell that imitates photosynthesis opens up new applications for photovoltaics. Click here to read more.