Functionalized triplet emitters for electro-luminescent devices

Abstract

This invention pertains to organo-metallic complexes for opto-electronic and sensory devices and their use in such opto-electronic and sensory devices. The organo-metallic complex (triplet emitter) of the invention consists of a metal center and chelate ligands. At least one of these chelate ligands comprises an aromatic or fused aromatic ring(s). Each of these ligands is covalently substituted with at least one, preferably two charge transport groups (ctg). The metal center can additionally be coordinated by a spectator ligand. The presence of two ctgs at each ligand results in distinct advantages - in particular for applications in organic light emitting diodes (OLEDs) - compared to complexes known in the state of the art: - The charge transport units facilitate hole and / or electron transport to the molecular center and allow for efficient exciton formation directly on the emitter complex. - The presence of the ctgs on each ligand provides a good shielding with respect to interactions to the environment. Thus, emission quenching is strongly reduced and materials with high emission quantum yields are obtained. - The presence of the ctgs on each ligand increases the separations between the emitting cores of different molecules and thus reduces undesired quenching by triplet-triplet annihilation or self-quenching effects. - The complexes of the invention are highly soluble in many organic solvents and thus are well suited for wet-chemical processing.

Description

Background technique [0001] Since the discovery of electroluminescence in organic materials, high-efficiency electroluminescent devices using small molecules, especially heavy metals containing complexes, have been extensively studied [tang et al. Appl. Phys. Lett. 1987, 51, 913]. Organic optoelectronics based on heavy metal-containing materials have been significantly developed. Efficient OLEDs with purely organic materials are difficult to come by because only 25% quantum efficiencies can be obtained due to spin-selection rules. However, the majority of excitons formed in OLEDs are triplet excitons (75%), which in purely organic emitters would dissipate as heat. As a result, the quantum efficiency of electroluminescence (EL) is severely limited. Therefore, during the past decade, research on OLED materials has focused on triplet excited-state light-emitting materials [eg, see: H. Yersin, Highly Efficient OLEDs with Phosphorescent Materials, Wiley-VCH, Weinheim 2008]. By u...

AI Technical Summary

Problems solved by technology

However, polymeric materials are not monodisperse and defect sites inevitably arise during synthesis

These defects will adversely affect the stability of the material and the performance of the device

Images