Absorption Enhancement of a Thin Silicon Film with a 3D Photonic Band Gap Crystal Back Reflector

Currently, the efficiency of thin silicon film solar cells is constrained by a limited intrinsic absorption of silicon. The efficiency could be significantly increased by using a highly efficient back reflector that sends unabsorbed light back into the solar cell [1]. As an interesting candidate for a back reflector, we study here a thin 3D photonic band gap crystal [2, 3] that forbids light within the band gap for all directions and for all polarizations.