Versatile, Benzimidazole/Amine‐Based Ambipolar Compounds for Electroluminescent Applications: Single‐Layer, Blue, Fluorescent OLEDs, Hosts for Single‐Layer, Phosphorescent OLEDs

Abstract

A series of compounds containing arylamine and 1,2‐diphenyl‐1H‐benz[d]imidazole moieties are developed as ambipolar, blue‐emitting materials with tunable blue‐emitting wavelengths, tunable ambipolar carrier‐transport properties and tunable triplet energy gaps. These compounds possess several novel properties: (1) they emit in the blue region with high quantum yields; (2) they have high morphological stability and thermal stability; (3) they are capable of ambipolar carrier transport; (4) they possess tunable triplet energy gaps, suitable as hosts for yellow‐orange to green phosphors. The electron and hole mobilities of these compounds lie in the range of 0.68–144 × 10−6 and 0.34–147 × 10−6 cm2 V−1 s−1, respectively. High‐performance, single‐layer, blue‐emitting, fluorescent organic light‐emitting diodes (OLEDs) are achieved with these ambipolar materials. High‐performance, single‐layer, phosphorescent OLEDs with yellow‐orange to green emission are also been demonstrated using these ambipolar materials, which have different triplet energy gaps as the host for yellow‐orange‐emitting to green‐emitting iridium complexes. When these ambipolar, blue‐emitting materials are lightly doped with a yellow‐orange‐emitting iridium complex, white organic light‐emitting diodes (WOLEDs) can be achieved, as well by the use of the incomplete energy transfer between the host and the dopant.

Blue Light Emitting Polyphenylene Dendrimers with Bipolar Charge Transport Moieties

“…Therefore, it is reasonable to expect that a dendrimer with PCs of both hole and electron (bipolar) transport properties could further facilitate charge injection and transport and improve device performance. A good way to produce a bipolar transporting material is to introduce both donor and acceptor components in a single molecule, a technique which has been frequently utilized to make bipolar small-molecular emitters [25,26] and host materials [27]. However, the number of donor-acceptor dendrimers with surface-tocore energy transfer is rather limited [28,29].…”

Efficient Blue Electroluminescence from a Single‐layer Organic Device Composed Solely of Hydrocarbons

“…Thus, the g f value was determined to be 35-52 %f rom EQE 5Me = 2.6 %. [12,15] We hope that au nique scientific endeavor based on the present study may flourish in the future by stimulating relevant studies. The substituent effects found in the EQE values (EQE 5oT = 1.8 EQE 5Me )c ould further be interpreted as ar esult of relations of f 5oT = 1.2 f 5Me and g 5oT = 1.5 g 5Me .T herefore, the substituents on the [5]CMPb ase materials were influential to both the fluorescent quantum yield and the charger ecombination.…”

“…[11,12,15] We used the [5]CMP macrocycle (5oT- [5]CMP) with 2'-tolyl (oT) substituents as the base material [12] and doped in the macrocycle, [ 3]CPhen 3,6 , [13] as the emitter.Asingle-layer device was fabricated with at hree-region setting of organic layers as follows:a node/undoped region (10 nm)/doped region (40 nm;2 0wt% dopant)/undoped region (10 nm)/cathode. [11,12,15] We used the [5]CMP macrocycle (5oT- [5]CMP) with 2'-tolyl (oT) substituents as the base material [12] and doped in the macrocycle, [ 3]CPhen 3,6 , [13] as the emitter.Asingle-layer device was fabricated with at hree-region setting of organic layers as follows:a node/undoped region (10 nm)/doped region (40 nm;2 0wt% dopant)/undoped region (10 nm)/cathode.…”

Synthesis and characterization of new polyfluorene derivatives: using phenanthro[9,10-d]imidazole group as a building block for deep blue light-emitting polymer

“…Thus, n-type unit is often introduced to increase the electron injection and transport property [28][29][30][31]. In recent years, imidazole derivatives are found to be an important functional group for adjusting the LUMO energy level [32]. For example, benzoimidazole-based compound 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi), which has a LUMO level of -2.40 eV, have been widely used in OLEDs as electron injection layer.…”