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

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In amorphous silicon (and its alloys) solar cells, because of the low carrier mobility and light induced degradation [1], 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 [2,3]. One of the candidates, surface plasmon assisted light confinement, has been demonstrated feasible with slight improvement [4,5]. However, huge metallic loss in metal structures hinders further improvement in SPP-assisted thin film solar cells [6]. 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.