Wave-optical studies of light trapping in submicrometre-textured ultra-thin crystalline silicon solar cells

Wave optics calculations are performed to determine the energy conversion efficiency of pyramidal textured thin c-Si solar cells. For an optimized 20 µm thick c-Si device backed by a silver mirror an efficiency of 21.3% is obtained. An alternative approach to back reflection, submicrometre phase-shifted pyramid texturization on the back surface instead of the lossy metal mirror is demonstrated to yield a higher efficiency of 21.5%. More significantly the phase-shifted texturization approach permits light to enter the solar cell from both the front and back surfaces. For 10 µm and 5 µm thicknesses, efficiencies of 20.4% and 19.0% are obtained, respectively. Thus, the architecture is amenable to fabrication of high-efficiency ultra-thin bifacial solar cells.