Microfluidic Self-Emissive Devices

Recently, electrogenerated chemiluminescence (ECL) cells and liquid organic light-emitting diodes (OLEDs) have attracted attention for unique self-emissive display applications. A solution-based emitting layer is used in the ECL cells, while a liquid organic semiconductor-based emitting layer is used in the liquid OLEDs. Conventional ECL solutions have been typically prepared by dissolving a single luminescent material in an organic solvent. These devices have a simple structure and been fabricated by sandwiching an emitting layer between two glass substrates with transparent electrodes. Although their structure and easy fabrication process are advantageous for large-area displays, the luminescent performances have been still significantly poor in comparison with state-of-the-art solid-state OLEDs which are one of the most developed self-emissive devices. Our research group has attempted to improve the performances of both the ECL cells and liquid OLEDs and proposed novel device structures. In this chapter, we will introduce our progress on developing the host-guest ECL solutions, the highly efficient ECL solution doped with an emitting assist dopant, and microfluidic self-emissive devices having the ECL solutions and liquid organic semiconductors. Various ECL emissions can be realized by doping fluorescent guest materials such as perylene, quinacridone, and anthracene derivatives into the host solution. The ECL performances of 5,6,11,12-tetraphenyltetracene (rubrene) were found to be significantly enhanced by adding a styrylamine derivative to the rubrene solution. The microfluidic devices, which can exhibit both ECL and electroluminescence (EL) emissions, have been fabricated by microelectromechanical system processes and heterogeneous bonding techniques.