A Novel Fluorene‐Triphenylamine Hybrid That is a Highly Efficient Host Material for Blue‐, Green‐, and Red‐Light‐Emitting Electrophosphorescent Devices

Abstract

TFTPA (tris[4‐(9‐phenylfluoren‐9‐yl)phenyl]amine), a novel host material that contains a triphenylamine core and three 9‐phenyl‐9‐fluorenyl peripheries, was effectively synthesized through a Friedel‐Crafts‐type substitution reaction. Owing to the presence of its sterically bulky 9‐phenyl‐9‐fluorenyl groups, TFTPA exhibits a high glass transition temperature (186 °C) and is morphologically and electrochemically stable. In addition, as demonstrated from atomic force microscopy measurements, the aggregation of the triplet iridium dopant is significantly diminished in the TFTPA host, resulting in a highly efficient full‐color phosphorescence. The performance of TFTPA‐based devices is far superior to those of the corresponding mCP‐ or CBP‐based devices, particularly in blue‐ and red‐emitting electrophosphorescent device systems. The efficiency of the FIrpic‐based blue‐emitting device reached 12 % (26 cd A–1) and 18 lm W–1 at a practical brightness of 100 cd m–2; the Ir(piq)2acac‐based red‐emitting device exhibited an extremely low turn‐on voltage (2.6 V) and a threefold enhancement in device efficiency (9.0 lm W–1) relative to those of reference devices based on the CBP host material.

Multifunctional Triphenylamine/Oxadiazole Hybrid as Host and Exciton‐Blocking Material: High Efficiency Green Phosphorescent OLEDs Using Easily Available and Common Materials

“…In this report, aiming to achieve high power effi ciency for PHOLEDs by using easily available materials and fabricating simple device structures, we designed and synthesized a new bipolar compound, namely m -TPAo -OXD, by connecting meta -position of phenyl ring in triphenylamine with the ortho -position of 2,5-biphenyl-1,3,4-oxadiazole to serve as a host material for green phosphor (ppy) 2 Ir(acac). The reason we chose triphenylamine (TPA) to replace carbazole is that triphenylamine has a high triplet energy (3.04 eV) and good hole-transporting ability like carbazole; [ 15 ] moreover, most triphenylamine compounds have higher HOMO levels (ca. 5.3 eV) than those of carbazole derivatives, [ 16 ] which are close to the work function of ITO or widely used hole transporting material 1, 4-bis[(1-naphthylphenyl)amino]biphenyl (NPB), and thus allowing effi cient hole injection.…”

A Highly Efficient Universal Bipolar Host for Blue, Green, and Red Phosphorescent OLEDs

“…It is fascinating to mention that by using BCPO as the common host, the performance of these basic-color devices, as summarized in Table 1, all appears to be among of the best ones that have been reported. To the best of our knowledge, there are few reports using a common host material for blue, green, and red phosphorescent devices, [18,26] but the performance of these devices are relatively low. However, as exhibited in Figure 2, the efficiencies of these devices reduce at high brightness.…”

3D Monodisperse Oligofluorenes with Non‐Conjugated Triphenylamine‐Based Cores: Synthesis and Optoelectronic Properties

“…Triphenylamine is a very reactive aromatic compound for the electrophilic substitution of fluorenol in the presence of a strong acid. [11][12][13] The para position with respect to the nitrogen is a reactive site whereas the ortho position has proven to be non-reactive as a result of steric hindrance. [10][11][12] The synthetic route used to synthesize PF 3 -TPA was similar to the procedure used for PF 3 -TPA 3 with (4-bromophenyl)di-ptolylamine as the starting material and triphenylamine as The structures and monodispersities of PF 3 -TPA 3 and PF 3 -TPA were identified by NMR, size-exclusion chromatography (SEC) and MALDI-TOF mass spectroscopy.…”

“…[11][12][13] The para position with respect to the nitrogen is a reactive site whereas the ortho position has proven to be non-reactive as a result of steric hindrance. [10][11][12] The synthetic route used to synthesize PF 3 -TPA was similar to the procedure used for PF 3 -TPA 3 with (4-bromophenyl)di-ptolylamine as the starting material and triphenylamine as The structures and monodispersities of PF 3 -TPA 3 and PF 3 -TPA were identified by NMR, size-exclusion chromatography (SEC) and MALDI-TOF mass spectroscopy. In the 1 H NMR spectrum of PF 3 -TPA 3 , the peaks at δ = 2.33 (3 H, singlet), 2.29 (3 H, singlet) and 2.05 ppm (16 H, multiplet) have been attributed to the resonance of the CH 3 groups in the tolyl moieties at the 9-position of the central fluorene units, the CH 3 groups in the TPA units and the methylene units in the octyl groups adjacent to the C-9 of the fluorene units.…”