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, n (ideality factor of J₀₂), and G_p (the parallel Ohmic conductivity) of the dark current-voltage characteristic 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 enable a separate investigation of factors influencing the depletion region recombination current and the diffusion current, which is governed by the bulk lifetime. Local I-V characteristics of special sites may be simulated.