Reciprocity between Charge Injection and Extraction and Its Influence on the Interpretation of Electroluminescence Spectra in Organic Solar Cells

In optoelectronics, luminescence under applied voltage and photocurrent generation under illumination are central to light-emitting diodes and solar cells, respectively. While in many cases these processes are perfectly reciprocal, and can be related via simple equations, in some relevant situations this symmetry disappears. The authors study the limits of reciprocity for several luminescence-based approaches commonly used to analyze organic solar cells, and find a few situations in which assuming reciprocity could be problematic.