Design and Synthesis of Phosphorescent Iridium Containing Dendrimers for Potential Applications in Organic Light‐Emitting Diodes

Abstract

Three phosphorescent dendrimers (IrC1, IrC3, and IrF2) with an iridium complex core and oligocarbazole or oligofluorene substituted ligands were synthesized and characterized. The structures of the oligocarbazole were designed to maintain high triplet energy of the ligands so that phosphorescence quenching in the resulting dendrimers can be prevented, while the oligofluorene in IrF2 resulted in undesired phosphorescence quenching. Best performance was obtained from an IrC3 based electrophosphorescent light‐emitting device with a maximum luminance of 13 060 cd · m−2 at a driving voltage of 11.5 V and a peak current‐efficiency of 4.3 cd · A−1 at a luminance of 3 400 cd · m−2, owing to its high PL efficiency, and efficient energy transfer between the iridium complex core and the ligands.magnified image

Structural Mimics of Phenyl Pyridine (ppy) – Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes – An Overview

“…Comparison has been made by Qin‐De Liu et al ., for the unsubstituted Ir(ppy) 2 (acac) complex with substituted oligocarbazole or oligofluorene (phosphorescent dendrimers (171–173), Figure ) with a same core . Dendrimer 171 and 172 contain hyperbranched oligocarbazole substituted dendrons, while dendrimer 173 contains oligofluorene substituted dendrons.…”

Dendrimers Chemistry and Applications: A Short Review

“…The polypropylene imine give rise to universal application in biology and as well as in material science. Moreover PPI dendrimers are also descibe as DAB-dendrimers and DAB describe to interior structure which generally supported on diamino butane [19].…”

“…Balzani and coworkers interrogated the fluorescence of fourth generation polymer (propylene amine) dendrimer designed with 32 dansyl units at periphery of it. The high fluorescence of all the dansyl units is quenched when Co3+ ion is integrated into dendrimers [19].…”

Recent Advances in Solution‐Processable Dendrimers for Highly Efficient Phosphorescent Organic Light‐Emitting Diodes (PHOLEDs)

“…Two highly branched yellow phosphorescent dendrimers containing carbazole‐based dendrons have also been reported ( DIr24‐G1 and DIr24‐G3 , Figure 25). 145 The carbazole moieties are linked together through the C3, 6 and 9 positions in order to maintain the high triplet energy of such dendron ligands to avoid undesired energy transfer from the phosphorescent core to them. Both dendrimers emit intense yellow in solution with almost identical PL spectra and emission peaks at around 550 nm.…”