Emissive Polyelectrolytes As Interlayer for Color Tuning and Electron Injection in Solution-Processed Light-Emitting Devices

Herein we present a solution-processed hybrid device architecture combining organic light-emitting diodes (OLEDs) and light-emitting electrochemical cells (LECs) in a bilayer architecture. The LEC interlayer promotes the charge injection from an air-stable Ag cathode as well as permits the color tuning of the device emission. To this end, we used an alcohol-soluble anionic polyfluorene derivative, the properties of which were investigated by absorption and photoluminescence spectroscopy as well as by cyclic voltammetry. The bilayer device exhibited operating voltages ∼6 V and a color tuning of the emission spectrum dependent on the LEC interlayer thickness. The hybrid devices presented a color emission ranging from the yellow (x = 0.39, y = 0.47) toward the green region (x = 0.29, y = 0.4) of the Commission Internationale de I'Eclairage (CIE) 1931 chromaticity diagram.