MODELING THE SPECTRAL RESPONSE OF THE QUANTUM-WELL SOLAR-CELL

The quantum well solar cell is an alternative to more conventional multiband gap approaches to higher cell efficiency. Preliminary studies have shown that the insertion of a series of quantum wells into the depletion region of a GaAs/AlxGa1-xAs p-i-n solar cell can significantly enhance the cell's short-circuit current. We present here a model for the spectral response of GaAs and AlxGa1-xAs p-n and p-i-n solar cells, with and without quantum wells, based on a standard solution of the minority-carrier equations. Particular emphasis is placed on modeling the absorption coefficient of the AlxGa1-xAs and of the quantum wells. We find that our model can accurately predict the spectral response of a wide variety of cells: both conventional p-n junctions in GaAs and AlxGa1-xAs, and various geometries of quantum well solar cell in AlxGa1-xAs/GaAs (x approximately 0.3). We discuss the strengths and weaknesses of the model and its underlying assumptions, and conclude by using the model to design p-i-n quantum well solar cells with higher short-circuit current outputs.