What photons tell us about solar cells – imaging diagnostic techniques

Photon emission by solar cells can be used for advanced device diagnostics with imaging techniques. We demonstrate that band-to-band luminescence, heat radiation, dislocation luminescence, and junction-breakdown-related radiation can be used to measure and detect local series resistances, hot-spots, defect-induced junction breakdown, and bulk-, surface- and grain-boundary recombination in silicon solar cells. First measurements of degradation and contamination of polymer solar cells are also presented.