Enhancement in response speed of OLEDs for visible light communications

By experiments, we have shown that large-area organic light-emitting diodes (OLEDs) exhibit slow dynamic response due to capacitor-like behaviors. To increase their response speed, one has to apply high bias voltage and reduce the device length. By way of simulations, we have found that the pulse separation is the critical factor determining the modulation speed of OLEDs for practical VLC applications. As the pulse separation is decreased, the ratio of the delay time of the second pulse to the delay time of the first pulse is found to be reduced, whereas the ratio of the peak luminance of the second pulse to the peak one of the first pulse is getting increased.