Konarka Technologies Inc., Lowell, Mass. (konarka.com), is set to build compact, renewable power sources for the U.S. Army from light-activated power polymers. Among other things, the plastic cells could let soldiers carry a few rechargeable batteries rather than numerous primary cells to power the electronics they carry into battle. "Our power plastic can help reduce the modern Army's logistics load," says Daniel Patrick McGahn, Konarka executive vice president and chief marketing officer.
Special operations soldiers, for example, can carry 70 to 100 lb of replacement batteries for night-vision goggles, GPS units, and two-way communicators, explains McGahn. "They carry a daily supply of primary batteries, but limited power capacity and the continual need for resupply can limit the mobility, range, and mission length required for effective field operations." Konarka photovoltaic cells use nanomaterials to convert absorbed sunlight and indoor light into electrical energy. This direct-current electrical energy can be used immediately, stored for later use, or converted to other forms of energy.
Traditional photovoltaic cells are made from rigid pieces of silicon. Konarka's chemistry-based cells are coatable, plastic, flexible photovoltaics that serve in many applications where traditional photovoltaics can't compete.
The photovoltaic products are literally printed onto rolls of plastic. Konarka scientists inject a dye into titanium dioxide, a white pigment commonly used in toothpaste and paint. Dye applied to a flexible material absorbs energy from both the sun and indoor light. This light energy travels through the titanium dioxide and a series of electrodes and is converted into electrical energy.
The process can imprint different colors on the photovoltaic material. A prototype tent under development for the military, for example, can be produced in camouflage colors. The cells can also be made with varying degrees of translucency. The production process is said to be environment friendly, uses existing coating and printing machines and technologies, and does not expose polymer substrates to harmful high temperatures.
As part of its work for the Army, Konarka also will perfect the printing of camouflage-patterned power plastic to maintain a low visible profile. "Coloring and patterning is unique to Konarka's technology," said Russell Gaudiana, Konarka vice president of research and development. "Other photovoltaics require camouflage covers for disguise, but that reduces light harvesting and power output. Our materials can be printed with the appropriate images while still maintaining their power generating capabilities, helping to protect soldiers in the field."