Thin film solar cells are less expensive to produce than silicon polycrystalline photovoltaic (PV) modules. Their flexible properties allow them to be laminated directly into walls and roofing material, creating a structure that has built-in PV without looking like a building made of solar modules. Unfortunately, thin film cells are also less efficient than their silicon counterparts.
Well, they were less efficient … until now.
Empa, the Swiss Federal Laboratories for Materials Science and Technology, has developed a flexible PV cell with an efficiency of 20.4%, breaking the previous record for flexible thin film (18.7%) and equaling the efficiency of today’s rigid and fragile silicon-based solar cells.
The thin film cells are based on CIGS (copper indium gallium selenide) semiconductors, which absorb over 99% of the incident light within the first micron of the material. This means that PV cells can theoretically be just a few microns thick … or should I say a few microns thin? With efficient thin film PV, engineers can integrate low-cost solar power into roofing material, cars, handheld devices – pretty much anything. Coupled with flexible displays and paper batteries, highly efficient thin film solar cells could lead to a generation of handheld devices that are thin enough to fit in wallet and never need to be recharged from an AC outlet.
Image: Empa
