Light-Emitting Electrochemical Cells: Mechanisms and Formal Description

Abstract

In 1995 Pei and coworkers reported the first light-emitting electrochemical cell (LEC). LECs are unique because of a simple device layout that does not compromise efficient charge injection and transport. This is achieved by the presence of mobile ions in the active layer. Despite the simple device layout, the device physics has proved to be extremely complicated. In this chapter, an overview is given of the development and methods towards the current understanding of LEC device operation. A large amount of experimental and modeling work in the last 20 years has proved that LECs can operate in different regimes, depending on charge injection and applied bias voltage. Processes related to this device operation range from electric double layer formation at the contacts to electrochemical doping and the formation of a dynamic p-i-n junction in the bulk of the active layer. We discuss these and, where possible, include formal descriptions of transient phenomena relating to the turn-on and stability of LECs on the one hand and on the other hand steady-state phenomena relating to the current density, potential distribution, and recombination properties of LECs.