The low-loss plasmonic mode for light confinement in silicon-based thin-film solar cells

In amorphous silicon (and its alloys) solar cells, because of the low carrier mobility and light induced degradation, a device of a thinner intrinsic layer has the advantage of higher carrier harvest in generating photocurrent. It is therefore critical to keep efficient absorption within limit thickness to both retain higher short-circuit current and filling factor of devices. Furthermore, the future trend of silicon-based thin film solar cells, double and triple junction solar cells, largely depends on micro-crystalline silicon layers. In order to enlarge market share, lowering the production cost though reducing the thickness of micro-crystalline silicon layers is the current interest in industry and academic research. Therefore, to keep a high level of photocurrent, thinner absorbing layers require efficient light management scheme. One of the candidates, surface plasmon assisted light confinement, has been demonstrated feasible with slight improvement. However, huge metallic loss in metal structures hinders further improvement in SPP-assisted thin film solar cells. Owing to the existence of optical loss in metallic structures, we propose a numerical method to analysis a multilayer system incorporating low-loss plasmonic modes with better light confinement. Meanwhile, we estimate the light-trapping effect in the textured transparent conducting oxide (TCO) which plays a coupling medium between sunlight and confined modes in solar cells.