White light from a single-emitter light-emitting electrochemical cell.

We report a novel and generic approach for attaining white light from a single-emitter light-emitting electrochemical cell (LEC). With an active-layer comprising a multifluorophoric conjugated copolymer (MCP) and an electrolyte designed to inhibit MCP energy-transfer interactions during LEC operation, we are able to demonstrate LECs that emit broad-band white light with a color rendering index of 82, a correlated-color temperature of 4000 K, and a current conversion efficacy of 3.8 cd/A. It is notable that this single-emitter LEC configuration eliminates color-drift problems stemming from phase separation, which are commonly observed in conventional blended multiemitter devices. Moreover, the key role of the electrolyte in limiting undesired energy-transfer reactions is highlighted by the observation that an electrolyte-free organic light-emitting diode comprising the same MCP emits red light.