Polyphenylnaphthalene as a Novel Building Block for High‐Performance Deep‐Blue Organic Light‐Emitting Devices

Abstract

A new member of polycyclic aromatic hydrocarbons named 1,2,3,4‐tetraphenylnaphthalene (TNa) is exploited and used as a potential building block in deep‐blue organic light‐emitting devices (OLEDs) for the first time. By incorporating TNa with phenanthroimidazole, three blue emitters named TNa‐PI, TNa‐BPI, and TNa‐DPI featuring different length of phenyl linkers are designed and synthesized via a facile approach, and systematically characterized with thermal, morphological, theoretical, photophysical, electrical, and electroluminescent (EL) studies. The new fluorophores show intramolecular charge transfer properties in excited state evidenced by positive solvatochromic effect in emission. Theoretical calculation suggests that TNa serves as an electron acceptor in the new molecules. All the new materials can emit intense deep‐blue fluorescence in thin film and show bipolar carrier transport properties, with electron conductivity much better than that of hole. Nondoped OLEDs based on TNa‐DPI exhibit excellent EL performance with a maximum external quantum efficiency (EQE) of 5.78% and deep‐blue emission with color purity of (0.152, 0.085). Furthermore, in the 30 wt.% doped device, TNa‐PI emits efficient violet‐blue EL with Commission Internationale de l'Èclarage coordinates of (0.156, 0.043) and shows a decent EQE of 2.52% at a practical brightness of 1000 cd m−2.

Effects of Injection Current on the Modulation Bandwidths of Quantum-Dot Light-Emitting Diodes

“…The highest external quantum efficiency (EQE) of the QLED achieved is 9.2%. The luminance characteristics of our QLEDs compare favorably with those of the OLEDs [21]- [23]. To our knowledge, this is the first report of the investigation of the modulation bandwidths of the QLEDs.…”

Violet-Blue Aggregation-Induced Emission Emitters for Non-Doped OLEDs with CIEy Smaller than 0.046

“…It is also worth noting the outstanding EQE value of the TPBCzC1-baesd OLED also represents the best results for violet-blue OLEDs with CIEy < 0.046 based on fluorescent materials ( Figure 6C and Table 2). [44][45][46][47][48][49] Moreover, all devices exhibit a very low efficiency roll-off probably because the radiative transition channels are activated and the non-radiative transition channels are inhibited in the aggregate state, confirming the excellent efficiency stabilities of the devices (Figures 6A and S7).…”

“…This work [44] 3.0 (0.158, 0.039) 1.76/-423 0.47/0.45 0.32/-PIMNA [45] 3.8 (0.160, 0.034) 2.43/2.42 412 0.51/---TAZ-4Cz [46] 3.9 (0.160,0.040) 2.48 412 0.65/-0.58/--TPI-Bz [47] 3.2 (0.162,0.043) 1.5/-420 0.5/-0.45/--TNa-PI [48] 3.4 (0.157,0.041) 2.63/2.40 428 0.87/0.80 0.73/0.36 -tDIDCz [49] 3.…”

Ternary Acceptor–Donor–Acceptor Asymmetrical Phenanthroimidazole Molecule for Highly Efficient Near‐Ultraviolet Electroluminescence with External Quantum Efficiency (EQE) >4 %

“…In general, most blue emitters tend to emanate redshifted and broad emission in the solid state due to intermolecular interactions, leading to poor color purity and reduced PL and EL performance . Moreover, the wide energy gaps of blue emitters also cause poor carrier injection/transportation and lower PL quantum yields (PLQYs) .…”

“…In general, most blue emitterst end to emanate redshifted and broad emission in the solid state duet oi ntermoleculari nteractions, leadingt op oor color purity and reduced PL and EL performance. [7][8] Moreover,t he wide energy gaps of blue emitters also cause poor carrieri njection/transportation and lower PL quantum yields (PLQYs). [9][10] These reflect the contradiction between opticala nd electrical properties, which gradually become predominant under increasingly stringent requirements on materialp erformance and has arousede xtensive interest in selectivep hotoelectronic modulation approaches.…”