Photovoltaic absorption enhancement in thin-film solar cells by non-resonant beam collimation by submicron dielectric particles

We propose the enhancement of the photovoltaic absorption in thin-film solar cells using densely packed arrays (not obviously regular) of non-absorbing submicron or micron-sized dielectric spheres located on top of the cell. The spheres can decrease reflection forming an effective blooming layer. Simultaneously, they can suppress the transmission through the photovoltaic layer transforming the incident radiation into a set of collimated beams. The focusing of the light inside the photovoltaic layer allows enhanced absorption in it leading to the increase of the photovoltaic current. Every sphere focuses the incident wave separately - this mechanism does not require collective effects or resonances and therefore takes place in a wide spectral range. Since the fabrication of such the coating is easy, our light-trapping structure may be cheaper than previously known light-trapping ones and perhaps even than flat anti-reflecting coatings.