Thin film silicon solar cells with non-simple integral period ratio between front and back gratings

We propose an ultra-thin amorphous silicon solar cell with dual-interface gratings of non-simple integral period ratios. The non-simple integral period ratio structure (NIPRS) shows a broad absorption band compared to the simple integral period ratio structure (SIPRS). Both the front and back gratings couple light into different optical modes in wavelength ranges that do not overlap. An integrated absorption of 67.2% is achieved when the thickness of the active layer is 100 nm.