Color control of electrochemiluminescence based on duty ratio of applied waveform voltage

In this research, we succeeded in controlling the light-emitting color obtained from the light-emitting surface of an organic electrochemiluminescence (ECL) device with a duty ratio of the applied voltage. The color change was based on the absorption of light by the light-emitting layer. Because we were able to control the light-emitting relative quantities in each electrode by changing the duty ratio. Long light-emitting lifetime will be expected in the future, because the light-emitting material used was poly(3-hexylthiophene-2,5-diyl) (P3HT), a conductive polymer. We fabricated the ECL device with a light-emitting layer thickness of 25.0 µm. In this device, the ECL color was changed from orange to red by changing the duty ratio from 50 to 10%. More ECL colors are expected to be realized by selecting the light-emitting material with appropriate absorption and ECL spectra.