Dye-based organic PVs could remove need for batteries

Wales-based G24 Innovations (G24i) has achieved what may be a record efficiency for dye-based organic photovoltaic (PV) cells of 26 per cent.

The technology is designed to be used indoors in consumer electronic devices such as wireless keyboards, foregoing the need for batteries.

For this reason, the company says standard test conditions used to obtain efficiency measures — generally an irradiance of 1,000W/m2 with an air mass at 1.5 spectrum and cell temperature of 25ºC — are simply not suitable.

‘If you’ve got a device that works at very high light levels with a high efficiency, but doesn’t then carry that efficiency down to the lower light levels, it isn’t going to work as well as you think it is,’ said G24i technology officer Mark Spratt.

Unlike silicon PVs and solid organic semiconductor PVs, dye-based solar cells use nanoparticles in electrolyte suspensions. G24i has recently developed a new composition of dye and electrolyte to achieve a conversion efficiency of 26 per cent — a claimed improvement on the previous record for this type of cell, which stood at 15 per cent.

In its tests, G24i used energy-efficient GE Polylux 827 fluorescent lamps at 200 lux as a source, which generated 16.8 microwatts through PV.

This would be suitable for powering devices such as wireless keyboards, which need to power radio-frequency signals, remote controls and eventually things such as phones and tablet computers if efficiency can be further improved.

‘When we were looking at different keyboards on the market, there was a 10-fold difference in the amount of power they required,’ said Spratt.

‘The ones that require high power can’t be run from photovoltaics indoors, so the companies that can adopt this and get rid of the batteries are those that have already made moves into low-energy electronics, with particular chipsets that allow you to boost voltage.’

G24i also makes use of supercapacitors for temporary energy storage in some of the prototype devices it has built for potential clients.

‘The first step is a paper feasibility study, based upon what the energy requirements of the device are, how much of our material we will need and if we are in the right ballpark. Then we’ll start looking at putting together a prototype,’ said Spratt.