Display device with dual emissive and reflective modes

A display device with dual electroluminescence and electrochromic display functions is described. The device consists of two layers of polymeric thin films, one of which is an electrochromic polymer and the other an electroluminescence polymer, that are sandwiched between two electrodes. Both polymers are blended with a solid electrolyte. The device functions as an electroluminescence device when positively biased, and as an electrochromic device if biased negatively instead. The measured current density for the electrochromic mode of operation was found to be two orders of magnitude lower than that for the electroluminescence mode. This functional duality demonstrates the successful combination of the option of light-emitting display and the power saving electrochromic mode for portable devices.