Solar cells are widely used in a wide range of diverse applications. Numerous principles of operation and fabrication technologies have been developed aiming at maximum efficiency, long life and low-cost. Solar cells are based on either micro-crystalline Si or on thin films applied on low-cost substrates, typically glass. The mostly studied and commercially exploited thin film solar cells are based on amorphous-Si, CdTe or CIGS (Copper Indium Gallium Selenide). The performance and fabrication cost of a solar cell depends strongly on two parameters: the composition and thickness(es) of active layer(s).

In several cases, stack of thin films are designed and explored for further improvement of the conversion efficiency. Thus, the accurate characterization of all active layers and anti-reflective layers (e.g. SiN on microcrystalline-Si) are crucial for the process optimization and penetration of the particular technology into the market.

FR-tools have been successfully employed in the characterization of layer stacks for solar cells. These tools can be tuned to cover any spectral regime within the 200nm-2500nm spectral range and can be equipped by certain accessories, e.g. integration sphere. By employing the appropriate FR-tool configuration the layer thickness and related optical properties (reflectance, colour, refractive index) are measured accurately and in short time.