Let the sun shine in [solar cell used as energy]

One of the major drawbacks of photovoltaic systems is the high generation cost. To address this problem, the US Defense Advanced Research Projects Agency initiated a study to create a thousand 10 cm/sup 2/ solar cells with over 50% efficiency, providing 500 mW in full sunlight, with reasonable manufacturing costs. Called the Very High Efficiency Solar Cell (VHESC) program, it hopes to take advantage of recent advances in nanotechnology by using engineered biological molecules to guide the assembly of inorganic materials into regular 3D structures, with dimensional and assembly control unattainable using current technologies. The program also hopes to benefit from the recent introduction of tools and processes to design and cost-effectively fabricate small-feature, complex, broad-spectrum non-imaging optics.