Nondestructive local analysis of current-voltage characteristics of solar cells by lock-in thermography

By evaluating dark lock-in thermography images taken at one reverse and three forward biases, images of all two-diode-parameters J₀₁, J₀₂, n₂ (ideality factor of J₀₂), and G_p (the parallel ohmic conductivity) are obtained. A local series resistance is explicitly considered and may be provided as a series resistance image, e.g. resulting from luminescence imaging. The results allow a separate investigation of factors influencing the depletion region recombination current and the bulk lifetime-governed diffusion current.