Recent Developments in Flexible Organic Light-Emitting Devices

As the demand for display technology in consumer electronics and lighting panels increases, thin, light, high-quality, and more cost-effective light-emitting devices are required. Organic light-emitting devices (OLEDs), satisfying the criteria exactly, have been considered the most promising next-generation display and lighting technique. In particular, an OLED based on flexible substrate enables the device to be applied to curved displays, electronic newspapers, wearable displays, and conceptual lighting panels, has been always in the spotlight both in science and industry. Great advances on flexible OLEDs (FOLEDs) have been made over the past three decades. The fundamental elements of FOLEDs including substrates, electrodes, fabrication and encapsulation techniques, as well as the strategies of efficiency improvement are discussed herein. Moreover, emerging electrodes such as graphene, carbon nanotubes, metal nanowire network and their composite, flexible perovskite light emitting devices, and stretchable light emitting devices are also considered. Finally, the future challenges and prospects for these devices are put forward.