Comparison between periodicity and randomness from an effective refractive index point of view; applicable to thin-film solar cells

In this paper, embedding plasmonic nanoparticles inside the solar cell s active layer, both in a periodic and in a random manner, is extensively investigated. The aim of this study is to investigate optical mechanisms inside the active layer as a consequence of nanoparticle inclusion as well as to compare periodicity and randomness in such structures, where the intended maximization of the ultra-broadband absorption renders the analysis complicated. To perform such study, an effective refractive index analysis is employed to simultaneously cover the influential parameters. The results show that although fully periodic structures are more desirable in narrow-band applications such as grating-assisted waveguide coupling, random inclusion of plasmonic nanoparticles in the solar cell s active layer yields a much higher optical absorption. Furthermore, random inclusion of nanoparticles is easier and much cheaper than periodic inclusion to implement in solar cell fabrication.