Effect of nonhomogeneous intrinsic layer in a thin-film amorphous-silicon solar cell

The intrinsic layer in an amorphous-silicon solar cell is usually several orders of magnitude thicker than the p- and n-layers to increase the electron-hole pair generation in the intrinsic layer and to decrease the recombination losses in the p- and n-layers. We hypothesized that a nohomogeneous intrinsic layer may trap the incident light better and increase the generation rate of charge carriers. The nonhomogeneity can be introduced by varying the composition of amorphous silicon alloys during chemical vapor deposition. The effect of intrinsic layer nonhomogeneity of various schemes was studied theoretically on the short-circuit current of a single-junction thin-film amorphous-silicon solar cell. The absorption of light was calculated using the rigorous coupled-wave approach for an AM1.5 solar irradiance spectrum for a wavelength range of 400-1100 nm. An antireection coating consisting of two layers of homogeneous dielectric materials was also used. The backing metallic layer of the solar cell was taken to be periodically corrugated. The short-circuit current of the solar cell with nonhomogeneous intrinsic layer was found to be higher than the solar cell with a homogeneous intrinsic layer.