Photonic Crystal Enhanced Light Trapping Solar Cell

The invention entails the improvement of current thin film solar cell (TFSC) technology by the incorporation of diffractive gratings and Photonic Crystals (PhCs) to improve the overall optical efficiency of the solar cell. Thin film solar cell technology has attracted significant attention as a potential solution to high material costs associated with conventional wafer based devices. By their very nature TFSC reduces the amount of material needed to manufacture each solar cell device and hence ultimately reduce the cost per watt of output power. However the reduction in active photovoltaic material also leads to a reduction in cell efficiency. Light trapping affords the capacity to reduce the thickness of the active solar cell material while still maintaining in theory similar absorption characteristics as those of standard thicker wafer based cells. The new invention tackles the light trapping issue by employing PhCs and diffraction gratings to increase the light trapping capacity of TFSC structures. In our design we employ a specially engineered stopband material which is designed to allow only for the propagation of normally incident light waves.