Light-trapping Optimisation Framework Based on Fourier-space Grating Design for Coupling to Waveguide Modes in an Ultra-thin Solar Cell

Ever-thinner solar cells are currently of interest to the photovoltaics community and demand the introduction of light-trapping techniques to retain a competitive photovoltaic performance. This work presents a framework for a guided light-trapping design applied to an ultra-thin (< 100 nm) solar cell. The framework is based on a fundamental study of the waveguide modes supported by a realistic device architecture. Mode-coupling is ensured by introducing a scattering layer according to its Fourier spectrum. The framework can be applied to any device architecture and for single or multiple wavelength absorption enhancement, having the flexibility to attain high-efficiency in ever-thinner photovoltaics.