Microfluidic organic light-emitting devices using liquid organic semiconductors

Since a first liquid organic light-emitting diode (liquid OLED) was proposed by Xu and Adachi in 2009, liquid organic semiconductors have been considered to be promising materials for novel electronic device applications. Although the luminescent characteristics of liquid OLEDs have been improved over the past few years, from the viewpoint of device structure, there are technical challenges associated with multicolor light emissions on a single device. In general, liquid OLEDs are simply fabricated by sandwiching a liquid emitter between two electrode-patterned glass substrates, and the thickness of the emitting layer is controlled with single-μm-thick spacer materials. Therefore, the development of integration method for multiple liquid OLEDs on a single device is an important step toward next-generation liquid-based displays. This chapter provides a brief overview of the authors' own recent researches on the microfluidic OLEDs which are novel liquid OLEDs combined with microfluidic technology. The following topics are discussed in this chapter: research background, fabrication methodologies for single-μm-thick electro-microfluidic devices using a novel exposure method and a heterogeneous bonding technique through the use of self-assembled monolayers, and demonstration of multicolor microfluidic OLEDs with the pyrenebased liquid organic semiconductors. The proposed microfluidic OLEDs are believed to open a new possibility for future liquid-based electronic devices.