Konarka Technologies

From The Engineer, 15 September 2003
Light infantry

US troops could soon be using lightweight plastic solar panels based on nano-engineered particles to power their battlefield equipment.

The US Army is funding prototypes of a power technology developed by Massachusetts-based Konarka, a specialist in photovoltaic systems, in a bid to reduce the number of batteries soldiers need to carry into combat.

Konarka's solar cells use nano-scale particles of titanium dioxide (Ti02) as their basic semiconductor material. Mounted on a flexible polymer, the Ti02 is coated with a film of light-absorbing dye and embedded in an electrolyte between electrical contacts. When a photon of light hits the dye it oxidises it, forcing an electron to leave the dye molecule. Hence a current is created.

According to Konarka, its devices can use a wider range of the light spectrum than conventional solar cells, allowing them to convert indoor artificial lighting as well as sunlight into energy.

Konarka has developed a process called 'cold sintering' which allows the materials used in its cells to be produced under relatively low temperature conditions.

This means that lightweight, flexible plastics can be used rather than glass or silicon - the only materials able to withstand the high temperatures of the conventional manufacturing process without disintegrating.

The US Army said it was this flexibility which attracted it to the technology. Military planners are concerned at soldiers' reliance on batteries to power the increasing amount of portable electronic equipment they carry into battle. This will typically include communications equipment, satellite positioning devices and combat aids such as range-finders.

This places a heavy physical burden on the soldiers, who are likely to be laden down with avariety of disposable and rechargeable power sources.

Under the development agreement, Konarka will build prototype power cells specifically designed to power military equipment. These will be tested by the army, and if successful could enter service within three years.

The US Army eventually hopes to use solar cells to make each soldier self-sufficient for electrical power. It said it may be possible to incorporate ultra-thin solar cells into uniforms, removing the need to carry additional power equipment.

Konarka is also developing a wide range of civilian applications, which it hopes will offer an alternative power source for a number of everyday electronic devices.

It claims manufacturing of power cells using cold sintering is quicker and cheaper than under other methods, opening the way for cost-effective mass production.