Nanoscale investigation of light-trapping in a-Si:H solar cell structures with randomly textured interfaces

Abstract

Light trapping in thin-film silicon solar cell arising from randomly textured ZnO front contact layers is investigated in the optical near-field experimentally and theoretically. The experimental data are obtained from near-field scanning optical microscopy, theoretical data are calculated using rigorous diffraction theory. The surface of the randomly textured ZnO consists of statistically distributed craters with different shapes. Along the rims of the craters light localizations are found. Photon jets emerge from the vertices of the surface profile. From the theoretical study, the local absorption enhancement is calculated. The results provide important insight into the local effects of light trapping in thin-film optoelectronic devices and strategies for optimizing the external quantum efficiency in thin-film silicon solar cells are discussed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.