Extending the 1-D Hovel Model for Coherent and Incoherent Back Reflections in Homojunction Solar Cells

In this paper we extend the analytical drift-diffusion model, or Hovel model, to model the electrical characteristics of solar cells incorporating a back mirror. We use a compact summation approach to derive modified optical generation functions in Homojunction solar cells, considering both coherent and incoherent reflections from the back reflector. These modified generation functions are then used to derive analytical formulae for the current-voltage characteristics of mirrored solar cells. We simulate the quantum efficiency of a simple GaAs np diode with a planar gold back reflector, and compare the results with the standard Hovel model using a generation function given by the Beer-Lambert law. Finally, we use the model to simulate the performance of a real GaAs solar cell device fabricated using an epitaxial-lift-off procedure, demonstrating excellent agreement between the simulated and measured characteristics.