Charge Transport in a Highly Phosphorescent Iridium(III) Complex‐Cored Dendrimer with Double Dendrons

Abstract

The charge transporting properties of a phosphorescent iridium(III) complexcored dendrimer, with two dendrons attached to each ligand of the core are reported. The results show that the high photoluminescence quantum yield of this material is obtained without compromising charge transport. The hole mobility values are reported over a wide range of temperatures and electric fields using the charge-generation layer time-of-flight technique. The results are analysed using the Gaussian disorder model (GDM), the correlated disorder model, the polaronic correlated disorder model, and the short-range correlated Gaussian disorder model. It is found that the GDM model gives the most comprehensive description of hole transport in this material. In spite of its larger size, the hole mobility of the doubly dendronised material compares favourably with that of a smaller singly dendronised material, and its spherical shape leads to low energetic disorder and clearly non-dispersive charge transport. This shows how molecular shape can be used to combine favourable photoluminescence and charge-transporting properties.

Synthesis and Investigation of Electro-Optical Properties of H-Shape Dibenzofulvene Derivatives

“…For this reason, hole-mobility was measured by the space-charge-limited current (SCLC) method. SCLC is one of the most widely used techniques [ 44 , 45 ] to measure charge mobility in the direction perpendicular to the film, which is the direction most relevant for photovoltaic applications or light emitting diodes [ 46 , 47 ]. Hole-only devices having the following structure: ITO/PEDOT:PSS/Hx/MoO 3 /Au, were realized and characterized under the same experimental conditions, such as in the dark, in a vacuum (10 −3 mbar) and at a controlled temperature.…”

Charge transport in a two-dimensional molecular organic semiconductor

“…7,[15][16][17] To evaluate this, charge carrier mobilities were also measured using the charge generation layer time-of-ight (CGL-TOF) method. 18,19 Fig. 4 shows the hole photocurrent transient for an as-cast lm on linear and log-log scales (inset), at room temperature and for an applied electric eld E ¼ 3.3 Â 10 4 V cm À1 .…”

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

“…Another approach to reducing the molecular interactions is increasing the density of dendrons close to the phosphorescent core by introducing dendrons into the phenyl and the pyridine rings of its ligands to form a “double dendron” structure, such as DIr1‐DDG1 (Figure 4). 106 Clearly, the six first‐generation dendrons in DIr1‐DDG1 can form a “spherical” cover (Figure 5), which can completely encapsulate the phosphorescent cores in the center and effectively block their interaction through the site‐isolation effect 107. Hence, a neat film of DIr1‐DDG1 can exhibit a remarkable PLQY of 70 %, which is even comparable to that of its solution (ca.…”