Numerical method to separate the photo-current and contact injection current in solar cells

The principle of superposition is a well-known method used in the analysis of current transport under dark and light conditions for several different types of solar cells. However, this principle assumes that the photo-current is voltage independent and the contact injection current is generation independent, which restricts its validity. The superposition principle cannot, however, be applied to most thin film solar cells as the above mentioned assumptions are not generally valid. In order to address this issue, we describe a novel numerical modeling approach that allows independent computation of the photo-current and the contact injection current components of the total current under illumination. Then, using several test cases where the principle of superposition breaks down, the usefulness of this modeling approach is demonstrated.