Enhancement of light absorption efficiency of amorphous-silicon thin-film tandem solar cell due to multiple surface-plasmon-polariton waves in the near-infrared spectral regime ∗

The reflectances of a thin-film solar cell were computed, using the rigorous coupled-wave approach, as functions of the angle of incidence and the free-space wavelength for illumination by linearly polarized plane waves. A tandem solar cell made of amorphous-silicon alloys was considered. The metallic back-reflector was taken to be periodically corrugated. Both the simple and the compound periodic corrugations of the metallic back-reflector (surface-relief gratings) were investigated. Lowreflectance bands in the reflectance spectrums were correlated with the solutions of the underlying canonical boundary-value problem to delineate the excitation of multiple surface-plasmon-polariton (SPP) waves. For the standard AM1.5 solar irradiance spectrum, we found that the light absorption efficiency in the near-infrared spectral regime can be increased up to 100% when multiple SPP waves of both linear polarization states are excited.