A Survey on Recent Advances in Organic Visible Light Communications

Visible light communication (VLC) employs light emitting diodes (LEDs) to provide illumination and data communications simultaneously. Organic LEDs (OLEDs) employing small molecules and long-chain polymers PLEDs, have been gaining attention within the VLC research community due to their inherent advantages such as flexible substrates and low-cost manufacturing. However, the carrier mobility of organic semiconductors is much slower than the devices composed of metal alloys, such as gallium nitride, thus leading to a restriction in the OLED modulation bandwidth. The manufacturing processes, materials and the photoactive size of the devices can affect the raw bandwidth of OLEDs. To increase the transmission speeds, novel approaches have been proposed including equalization techniques, signalling schemes and the optimum driver circuits. The paper provides a survey on the evolution of OLED-based VLC systems, and the respective challenges and recent progresses.

I. Introduction

Visible light communications (VLC) is a new wireless technology for transmitting data by means of intensity modulation of light emitting diodes (LEDs). VLC offers advantages over the radio frequency (RF) technologies such as inherent security, immunity to RF-based electromagnetic interference, license-free spectrum and high scalability [1], [2]. LEDs are based on both inorganic and organic materials, with the latter being explored for a range of applications [1]. LEDs produce white light with either a package that contains individual red, green, and blue (RGB) LED chips or using a blue LED that has a cerium-doped yttrium aluminium garnet (Ce:YAG) yellowish phosphor encompassing the photoactive area, known as white phosphor LEDs (WPLEDs) [3]. The wide spread use of LED lights at home, offices, streets, and public places, acts as a good motivator for utilisation of VLC for indoor and outdoor applications [1]. For example, in airplanes, hospitals, intelligent transportation systems [4], indoor localization [5], [6], machine-to-machine communications or the internet of things (IoT) [7], and underwater communications [8].