Electroswitching of emission and coloration was achieved by a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV2+), indicating that the complex-molecule combination could be used as a display material with dual emissive and reflective modes. The coloration of the material was associated with the electrochromism of HV2+. Emission control was found to be possible due to the electrochromism of HV2+ via intermolecular energy transfer from the excited state of the Eu(III) ion to the reduced state of HV+. By using this mechanism, dual emissive and reflective representation of numerical characters were demonstrated. 
Electrochemically-switchable emission and absorption by using luminescent Lanthanide(III) complex and electrochromic molecule toward novel display device with dual emissive and reflective mode