Fabrication And Characterization Of Organic Light Emitting Transistors Based On Bi-Layered Heterojunctions

Organic light-emitting transistors(OLETs) are multifunctional devices that integrate light emission with the current modulating function of a transistor. OLETs show great potentiality for technological applications such as flat panel displays, optical communications, solid-state lighting, and electrically pumped organic lasers.To achieve high performance, OLETs need not only high mobilities, but also balanced transport of holes and electrons. By adjusting the N-type and P-type materials of a hetero junction, the mobilities of holes and electrons can be balanced effectively.In this thesis, OLETs with a bi-layered heterojunction are studied. First of all, single-layer organic field-effect transistors (OFETs) based on N-type material P13 and P-type material DH6T are fabricated respectively. And the characteristics of the devices are investigated.Then, bi-layered OLETs based on P13 and DH6T are fabricated. By inserting a layer of MoO3 to modify the Au electrodes, the mobilities of holes are improved, and the devices achieve balanced transport of holes and electrons. Besides, long-last stable light emission is observed from the devices.In addition, OLETs based on P13/Pentacene heterojunction are fabricated, and the devices show high performance. Bright green light can be observed from the devices with Ag electrodes.In the fifth chapter, a bi-layer organic insulation consisting of PMMA and cross-linked PVP is successfully used in the OLETs based on P13 and DH6T. The organic insulating layer effectively improves the mobilities of the devices, and its successful application provides a way to realize the fabrication of flexible OLETs. Besides, the stability of performance at high voltage of devices with the bi-layer organic insulation is successfully improved in this chapter.