So far, Solasta’s prototyping has been done on small cells. In the coming months, the company will work on scaling up its cells to conventional thin-film sizes. The company is also testing different substrate materials, including polymer nanowires, to determine which material provides scalability to large areas while supporting the best efficiencies. Naughton, the company’s chief technology officer, says the concept will work with any thin-film solar materials, but the company is focusing on amorphous silicon first.
The nanopillar architecture has another advantage in addition to efficiency when applied to amorphous silicon cells. “Amorphous silicon cells degrade in prolonged sunlight, reducing their efficiency by 20 to 30 percent,” says Naughton. But this degradation is much less pronounced in cells thinner than about 100 nanometers, such as Solasta’s, which should maintain their performance better over their lifetime.
The company will also develop the nanopillar architecture for new types of solar cells that take advantage of quantum phenomena at the nanoscale. The Boston College researchers recently demonstrated that ultrathin solar cells can allow “hot” electrons with very high energy levels to exit the cell. Even in thin cells, however, these electrons tend to lose their energy before they can escape. In the hope that the dual-path architecture of its nanopillars will solve this absorption problem, Solasta will work on developing nanopillar solar cells with ultrathin layers of silicon.