Lock-in thermography and nonuniformity modeling of thin-film CdTe solar cells

We present the lock-in thermography study of thin-film CdTe/CdS solar cells. Several major features of thermal signal are identified, such as much higher intensity for cells under illumination, considerable inhomogeneity, and a bright contour line corresponding to the higher intensity at the cell edge. Light soak stress is shown to increase the device lateral nonuniformity. We model the solar cell as a two-dimensional system of random diodes connected in parallel through a resistive electrode. The simulated current distribution maps are consistent with the thermography data.