Polymer Light-Emitting Electrochemical Cells with Bipolar Electrode-Dynamic Doping and Wireless Electroluminescence

This progress report reviews the background and recent developments of polymer light-emitting electrochemical cells (PLECs). The PLECs of interest have a planar configuration and contain bipolar electrodes (BPEs). A BPE is an electrically floating conductor immersed in an electrochemical cell that contains redox species. When the electrochemical cell is polarized with an externally applied voltage bias, coupled redox reactions are induced wirelessly at the extremities of the BPEs due to the development of a sufficient interfacial potential difference. BPEs can have a dramatic effect on the doping pattern and the emission profiles of PLECs. In a bulk homojunction PLEC containing a large number of dispersed micro-BPEs, the turn-on response and light output are greatly enhanced when multiple light-emitting p-n junctions form throughout the active layer. PLECs offer a solid-state platform on which the bipolar electrochemistry phenomena can be investigated, and the understanding of the complex PLEC processes can be improved. This progress report highlights several new BPE types as well as their potential applications for device performance enhancement and for the visualized screening of functional materials.