Efficiency enhancement in Si solar cells by textured photonic crystal back reflector

An efficient light-trapping scheme is developed for solar cells that can enhance the optical path length by several orders of magnitude using a textured photonic crystal as a backside reflector. It comprises a reflection grating etched on the backside of the substrate and a one-dimensional photonic crystal deposited on the grating. Top-contacted crystalline Si solar cells integrated with the textured photonic crystal back reflector were designed and fabricated. External quantum efficiency was significantly improved between the wavelengths of 1000 and 1200 nm (enhancement up to 135 times), and the overall power conversion efficiency was considerably increased. (c) 2006 American Institute of Physics.