Fig. 4: Current and temperature dependence of the singlet and triplet EL intensity of a dual-emitting OLED.

The current dependence (a, b) is shown at a temperature of 1.5 K and the temperature dependence (c, d) at a current of 10 μA. The lines show a fit to the data of the combined functional dependence of TSP and the Δg effect following Eq. (4). At higher currents and at low temperatures, a narrow feature is observed around zero field (gray areas), which is attributed to the effect of spin mixing due to hyperfine interactions. This gray region is excluded in the fitting procedure. The triplet intensity is quenched at high fields for the 50 K curves at 10 μA, so there is no meaningful fit possible.