Novel materials towards solution processible organic light emitting diodes

Organic light emitting diodes (OLEDs) have been a major area of research for nearly 20 years. The emphasis tends to focus on two aspects: the development of novel materials and the engineering of device structures. In the effort to apply new materials to OLEDs, the use of solution processible materials is of particular interest since solution processing provides a much more cost effective way to fabricate OLEDs than the conventionally used vacuum deposition. Continuing the effort to develop solution-processible materials, this dissertation describes the design and synthesis of metal containing emissive polymers, high triplet energy polymer hosts, and crosslinkable hole injection polymers, as well as their application in OLEDs.;The first chapter introduces the brief history of OLEDs, its operational principle, the standard device characterization method, and different types of materials used in OLEDs. The advantages and disadvantages of each type of materials are reviewed.;Chapter 2 describes the incorporation of a square planar platinum complex into polymer hosts through either physical doping or chemical attachment. Through adjusting the monomeric and excimeric emission from this platinum complex, high quality white light emission is achieved.;In chapter 3, the synthesis of hole transporting (HT), electron transporting (ET) and functionalized beta-diketone (Ln) monomers, as well as their living radical polymerization is described. These highly soluble random and block copolymers bearing bipolar transport moieties are either directly used as a matrix for doping or chemically functionalized with phosphorescent iridium complexes. The phase separation of block copolymers and the corresponding morphology effect on device performance are presented.;Chapter 4 details the synthesis and characterization of carbazole-based high triplet energy host materials. Polymer hosts with triplet energies higher than 3.00 eV are obtained and used in OLEDs.;Chapter 5 introduces a convenient way to fabricate solution-processible multi-layer OLEDs through crosslinking. The synthesis of both UV and thermal crosslinkable hole transporting materials is shown. Both materials are used in fluorescent OLEDs and they show comparable performance to the standard device fabricated by vacuum deposition. These materials have also been fabricated into highly efficient solution-processed phosphorescent OLEDs.