Optical and electrical modeling of an amorphous-silicon tandem solar cell with nonhomogeneous intrinsic layers and a periodically corrugated back-reflector

A tandem solar cell comprising two p-i-n solar cells made of amorphous-silicon alloys and backed by a periodically corrugated metallic back-re ector was theoretically investigated. The intrinsic semiconductor layers in both constituent solar cells were taken to be nonhomogeneous with linearly varying bandgap. An AM1.5 solar irradiance spectrum was incorporated in the nite-di erence-time-domain calculations (Lumerical^TM) to obtain the generation rate of electron-hole pairs, which was then used in Synopsys Sentaurus^TM to compute the electrical properties of the solar cell. The short-circuit current increases when the intrinsic layers are nonhomogeneous as compared to homogeneous intrinsic layers. However, electrical simulations showed that a new approach to modeling is needed that can take into account the continuously varying bandgap instead of considering it as piecewise uniform.