Effect of dendron structure on the luminescent and charge transporting properties of solution processed dendrimer-based OLEDs

Abstract

The energy transfer, PLQY, charge mobility, and OLED performance of blend films of first generation Ir(ppy)3-cored light-emitting dendrimers and dendrimeric TCTA-based hosts are found to be dependent on the dendrons and surface groups used.

Properties of Dual Emissive Dendrimers Based on ThermallyActivated Delayed Fluorescence Dendrons and a Phosphorescent Ir(ppy)3 Core

“…The reason for this is unclear although it has been observed in other dendrimer-based OLEDs. [33] It can be seen from the device characteristics that the OLEDs with the neat GG EML had a smaller roll-off in EQE with increasing luminance when compared to the BG containing devices (Figure 7b). We ascribe this to be at least in part due to the neat films of GG having higher hole and electron mobilities [(7.7 ± 1.4) × 10 -6 and (5.6 ± 1.0) × 10 -6 cm 2 V -1 s -1 , respectively -determined using a photo-Metal-Insulator-Semiconductor Charge Extraction by Linear Increasing Voltage (photo-MIS-CELIV)] [5b,22f,34] than the BG neat films [(1.4 ± 0.2) × 10 -6 and (1.3 ± 0.2) × 10 -6 cm 2 V -1 s -1 , respectively].…”

Effect of dendrimer generation and surface groups on the optoelectronic properties of green emitting bis-tridentate iridium(iii) complexes designed for OLEDs

“…When solvent mixtures were used, the proportions are given by volume. NMR spectra were recorded on Bruker Avance 300 MHz, Avance 500 MHz or Ascend 500 MHz spectrometers with chemical shifts (d) reported in parts per million (ppm) and are referenced to the residual solvent peak (deuterated chloroform, 1 H d 7.26 ppm, 13 C d 77.00 ppm, deuterated dichloromethane, 1 H d 5.32 ppm and deuterated dimethyl sulfoxide, 1 H d 2.50 ppm). Coupling constants (J) are given in Hertz (Hz) and are quoted to the nearest 0.5 Hz.…”

“…MP = 237 1C (decomp. ); l max (dichloromethane)/nm 276 (log/dm 3 mol À1 cm À1 5.20); 1 (16H, AA 0 BB 0 , SPH), 7.07 and 7.87 (8H, AA'BB 0 , SPH), 7.42 (4H, d, J = 1.5 Hz, G1-BPH), 7.53 (1H, br, ImLPH), 7.75 (2H, dd, J = 1.5 Hz, J = 1.5 Hz, G1-BPH), 8.02 (2H, brs, ImLPH), 8.39 (2H, s, G1-BPH), 8.72 (1H, s, G1-BPH), 9.47 (2H, brs, ImH), 11.57 (2H, brs, ImH); 13 C NMR (125 MHz, CDCl 3 ) 11.0(6), 11.0 (7) 4,4 0000 -Di-tert-butyl-5 0 ,5 00 0 -bis[4-(tert-butyl)phenyl]-[1,1 0 :3 0 ,1 00 :3 00 ,1 00 0 :3 00 0 ,1 0000 -quinquephenyl]-5 00 -carbaldehyde 6…”

“…It has been previously shown that dendron generation, surface groups, and/or the number of dendrons attached to the complex can be used to control solubility and intermolecular interactions. [10][11][12][13] In addition, dendrons composed of charge transport 14,15 or insulating units 16 have been reported, although in most cases the charge is transported via core-to-core hopping in neat films as the iridium(III) complex often has the smaller (relative to the dendron) redox potentials. However, one of the issues with attaching dendrons to bidentate ligands is that the dendrons are always pointing away from the central iridium(III) atom.…”

Dendritic polyphenylene AIEgens: fluorescence detection of explosives and stimulus-responsive luminescence

“…Due to the steric effect, the interior chromophores were usually protected from undesired intermolecular interactions and packing with other dendrimers. 11 As a result, most fluorophores within the dendrimer would be excluded from the notorious aggregation-caused quenching phenomenon owing to the shielding effect of dendrons. Owing to their superior luminescence properties, fluorescent dendrimers have been widely utilized in detecting metal ions, 12 volatile organic vapours, 13 and explosive substances.…”