The Development of Light‐Emitting Dendrimers for Displays

Abstract

Dendrimers are now an important class of light‐emitting material for use in organic light‐emitting diodes (OLEDs). Dendrimers are branched macromolecules that consist of a core, one or more dendrons, and surface groups. The different parts of the macromolecule can be selected to give the desired optoelectronic and processing properties. The first light‐emitting dendrimers were fluorescent but more recently highly efficient phosphorescent dendrimers have been developed. OLEDs containing light‐emitting dendrimers have been reported to have external quantum efficiencies of up to 16 %. The solubility of the dendrimers opens the way for simple processing and a new class of flat‐panel displays. In this Review we show how the structure of the light‐emitting dendrimers controls key features such as intermolecular interactions and charge transport, which are important for all OLED materials. The advantages of the dendrimer architecture for phosphorescent emitters and the way the structure can be varied to enhance materials performance and device design are illustrated.

Amplified spontaneous emission and lasing properties of bisfluorene-cored dendrimers

“…Over recent years, semiconducting conjugated dendrimers have attracted considerable attention for their application in organic light-emitting diodes ͑LEDs͒. 1 These branched macromolecules with a well-defined structure are typically composed of a light-emitting core and dendrons to which surface groups are attached. Their electronic properties are controlled by the core, which can be chosen from a large range of luminescent chromophores.…”

Light-emitting poly(dendrimer)s

“…The photoluminescence quantum yield (PLQY) of monomer (11) was measured as 1.5 % in degassed tetrahydrofuran. To confirm that this low PLQY value was due to the presence of a double bond the PLQY of 5, which does not have the vinyl group, was prepared by reaction of bromofunctionalised dendrimer 9 with benzene boronic acid under Suzuki conditions to give (5) in an 89% yield. The PLQY of 5 was found to be 43%.…”

“…Driving their development for displays is the fact that they have wide viewing angles, can form very thin devices, have low power consumption and in the longer term can potentially be used in flexible screens. There are three classes of light-emitting materials that have been developed for OLEDs, namely small molecules 3 , polymers 4 , and more recently dendrimers 5 . Small molecule light-emitting materials are processed into displays by vacuum vapour deposition.…”

A New Efficient Convergent Synthesis of Conjugated Aryl-containing Dendrimers

“…For example, the core in dendrimer can be selected to give the desired luminescence color, while the surface groups could be controlled to give the desired solubility. 10 Despite the large amount of research focused at dendrimers and the large number of prospects for their potential uses, very few dendrimer-based products have reached an industrial development stage. Among the reasons for the slow progress in this area are the multi-step synthetic routes commonly employed for the synthesis of dendrimers and the purification processes required to remove the excess of reagents and byproducts at each generation build-up.…”