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 Gp (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.