Random Plasmonic Nanowire Gratings for Enhanced Light Absorption in Organic Solar Cells.

The effects of random nanowire gratings on the light absorption of organic solar cells are studied. The gratings are deposited on the back silver electrode, causing the excitation of surface plasmonic modes. An advantage of such gratings is that they will not cause any blockage to the incident light; hence, they can be as dense as necessary. Using a finite-difference time-domain numerical method, several Monte Carlo experiments are tested, in two- and three-dimensional geometries. It is shown that cells with random gratings clearly outperform flat cells, i.e., cells without any gratings while their average efficiency is slightly below those of the optimized geometries. However, optimized geometries require nanoscale accurate deposition of grating nanowires and require expensive fabrication procedures. This suggests that random gratings can effectively replace nanoscale accurate geometries, with a slight tolerance of absorption efficiency. [ABSTRACT FROM AUTHOR]