Perturbation Theory for Solar Cell Efficiency I—Basic Principles

A streamlined method of calculating the sensitivity of a solar cell´s current and maximum power to small changes in device parameters is proposed. The method also introduces three sensitivity factors related to the effects of changes in the generation, bulk, and surface recombination rates on the maximum power, which are amenable to spatial plots in a device simulator. The analysis is rigorous to first order and generally applicable to multidimensional solar cells with injection-level-dependent lifetimes and surface recombination velocities, with or without “photon recycling,” under low injection level conditions at the maximum power point.