To make thin film solar cells have a higher efficiency than any of the previously experimented models, some Boston College researchers propose using nano-scale solar cells inspired by the working principle of coaxial cables. There’s a so-called “thick & thin” issue in making thin solar cells, which states that a solar cell has to be thick enough to collect light in sufficient amounts, and at the same time it needs to be thin enough to extract current from it.
“Many groups around the world are working on nanowire-type solar cells, most using crystalline semiconductors,” said co-author Michael Naughton, a professor of physics at Boston College. “This nanocoax cell architecture, on the other hand, does not require crystalline materials, and therefore offers promise for lower-cost solar power with ultrathin absorbers. With continued optimization, efficiencies beyond anything achieved in conventional planar architectures may be possible, while using smaller quantities of less costly material.”
Coaxial cables had been used in the mid 1800s, but those proposed by the researchers for use in solar cells are nanometric in size and built with amorphous silicon. With such an approach, the final solar cell is more than 8 percent efficient, which surpasses any nanostructured thin film solar cell built to date, as the team reports.
Conventional nano-sized solar cells suffer from an effect called “Staebler-Wronski light-induced degradation effect”, which is caused by their thickness. The new coaxial nano-structured cells solve this hurdle by being ultra-thin.
The Boston College researchers included Professors of Physics Krzysztof Kempa and Zhifeng Ren, as well as BC students and collaborators from Solasta Inc., of Newton, Mass., and École Polytechnique Fédérale de Lausanne, Institute of Microengineering in Switzerland.
Designing flexible and thin solar cells that are as efficient as classic ones, but less expensive is a step forward for any energy consuming application, starting with nano-scaled sensors and ending with car-embedded solar panels.
