Organic photonic devices utilizing nano-structured materials

Abstract

The characteristics of organic photonic devices with various kinds of geometrical nano-structures at the interface between organic materials, and also between the organic layer and metal electrode are investigated. A cutoff frequency of more than 20 MHz was observed for single-layer heterostructure organic photodetector (OPD) by applying a reverse bias electric field under the illumination of the red repetition pulse light. The mixed-layer heterostructure OPD with high photocurrent and high speed photoresponse is suitable for the application of optical link devices. An organic light-emitting diode (OLED) with a partial doping layer at the interface of heterostructure device can be expected to improve the modulation characteristics. The existence of interface between the organic layer and Cs or CsF results in low turn-on voltage for OLEDs. To achieve the efficient electron injection, it is necessary to exist Cs layer just on the organic layer. The efficient electron injection and the low turn-on voltage result from the coexistence of MgAg and CsF at the position of approximately 1 nm from organic layer. The poly(3-hexylthiophene) device with a cathode fabricated from Ag nanoparticles shows a photoresponse and a red emission in the reverse and forward bias regions, respectively. We demonstrated the possibility of polymer OLEDs using a cathode fabricated from Ag nanoparticles by wet processing.