Caltech Explores Plastic Solar Cells

The California Institute of Technology (Caltech) has recently developed solar cells made of 98% plastic, effectively using 1/50th of the normal semiconductor material required. More importantly though these solar cells have demonstrated over 90% efficiency, almost four times greater than traditional silicon-based solar cells.

The researchers at Caltech have discovered that by growing silicon wires in a polymer substrate the cells will maintain better flexibility while adding to its efficiency. Normally light is captured by regular solar cells and converted into electricity with a bulk of light bouncing away and essentially being lost. The added flexibility of these plastic cells will trap the light causing the light to bounce around inside a matrix until it is absorbed. As a result, more light will be absorbed and at a higher concentration.

Atwater explains, “The light comes in and is both directly absorbed by the wires, and some of the light bounces around in between the wires. And that bouncing around or multiple scattering in between the wires results in dramatically enhanced absorption. In fact, the absorption enhancement that we see is in” the range of 20 to 50 times the single-pass absorbance.”

Additionally, the flexibility of these plastic solar sheets presents a unique opportunity to curve and shape them along surfaces that are not traditionally flat. For instance, Atwater suggested the roof of a car could be a potentially useful application that would take advantage of this new material. They could also be integrated into roofing materials to save money on installation and ultimately making it even cheaper to go green.

These recent developments will have a profound impact in the solar sector and the renewable energy market as well. Solar technology has always been a viable source of energy for the future and this research only strengthens its case. Currently, the head of the research, Harry Atwater, is working on increasing the voltage and size of the solar cells so that they can be produced inexpensively as flexible sheets.