The light-emitting electrochemical cell (LEC) can be comprised of solely air-stable materials and feature a very simple and robust device structure in the form of a single-layer active material sandwiched between two electrodes. This renders the LEC technology highly fit for scalable and cost-efficient printing and coating fabrication under ambient air. The characteristic feature of LEC devices is the combination of mobile ions with the emissive organic semiconductor within the emissive layer. These mobile ions redistribute when a voltage is applied, and enable p-type electrochemical doping of the organic semiconductor at the anode and n-type doping at the cathode. With time, these doping regions grow in size and make contact under the formation of a p-n junction. The fact that Sym-DiDiKTa displays highly reversible electrochemical oxidation and reduction behaviour in the cyclic voltammetry experiments (Figure ) suggests that it could be fit for the task of the emissive organic semiconductor in a LEC device. Figure presents the steady-state EL spectrum recorded during the driving with a constant current density of 77 mA/cm 2 , with the lEL at 551 nm and the FWHM being 60 nm.