Earth-Toned Photovoltaic Device for Camouflaged Solar Power

Affords Solar-Energy-Harvesting Capabilities to Military Gear, Clothing, and Other Camouflaged Equipment

This photovoltaic device uses assemblies of polymer solar cells with different colors and color intensities, including green, brown and grey/black, to allow for custom-configured high-performance solar-energy-harvesting systems that blend in with the surface or environment of placement. The global solar energy market expects to approach an estimated $140 billion by 2023. Similarly, the demand for renewable energy sources continues to increase particularly in the U.S. military, due to rising energy distribution costs, foreign oil dependency, and the threat of energy supply disruptions. The U.S. military regularly outfits soldiers traveling on foot with multiple battery-powered devices over extended periods of time. However, the necessary batteries are often bulky and heavy and offer a limited device lifetime before the need to recharge. Furthermore, the batteries require the use of nonrenewable energy since available clean energy sources, such as photovoltaic devices, stand out in their surrounding environments and do not easily incorporate into other objects.

Researchers at the University of Florida have developed a lightweight photovoltaic system constructed from an assembly of organic polymer solar cells exhibiting earth-toned colors to provide a camouflaged renewable power source. The device integrates with various materials and surfaces and flexibly adapts to the environment of placement, blending into the location of placement.

Application

Lightweight solar-power system that readily integrates into various camouflaged environments

Advantages

• Uses earth-tone-color solar cells, providing a camouflaged assembly for use in military gear and other related applications
• Adapts to blend into the appearance of its location of use, offering unlimited camouflage opportunities
• Generates electricity through solar energy, limiting the need for conventional batteries in the field and reducing environmental footprint
• Consists of many individual solar cells across a larger device area, supporting color optimization of each pixel and easy replacement of defective pixels without the need to discard the entire device
• Incorporates organic solar cells, permitting lower fabrication and processing costs, better scalability, and lower weight than traditional inorganic solar cells
• Contains solar cells made from plastic substrates, providing mechanical flexibility for physical movement

Technology

This device creates a camouflaged appearance by utilizing individual solar cells that display a green, brown, or gray/black color based on the structure of the molecular chromophores lying within them, which provide their coloration. These molecular chromophores make up the donor-acceptor p-conjugated polymers of the device to form the photoactive layer of the solar cells. The initial polymers, PMB-250 and PMB-282, display a green or black color, respectively. When blended with a PCBM derivative, the polymers produce the additional brown or gray/black colors. PMB-250 mixed with the PC70BM forms a brown color while PMB-282 mixed with either PC60BM or PC70BM forms a gray to black color depending on the thickness of the solar cell active layer. Deposition techniques such as spin-coating, spray-casting, ink-jet printing or stamping integrate the polymers into the device.

Patent Issued: US 8,519,088