20.1% efficiency achieved on large area thin silicon wafer PV cell

The laser-grooved buried contact (LGBC) crystalline silicon solar cell has a selective emitter with excellent response to the solar spectrum in the wavelength range 300-900 nm. However, the cell efficiency is limited by a reduced response in the 900-1200 nm region of the spectrum due to the high recombination characteristics of the rear aluminium back surface contact and reduced internal reflection at this interface. The LGBC cell has now been fabricated with an aluminium laser-fired contact (LFC) through a passivating rear silicon oxide dielectric.

By Nigel Mason, Oliver Schultz, Richard Russell, Stefan Glunz and Wilhelm Warta, BP Solar.