A highly efficient violet-blue OLED with Rec.2020 CIEy based on an orthogonal phenanthroimidazole-substituted 1,2,4-triazole derivative

Abstract

A violet-blue OLED derived from an orthogonal phenanthroimidazole-substituted 1,2,4-triazole fluorophore achieved a high EQE of 6.01% and CIEy of 0.043, being close to the blue standard of Rec.2020.

High-Performance Ultraviolet Organic Light-Emitting Diodes Enabled by Double Boron–Oxygen-Embedded Benzo[m]tetraphene Emitters

“…Moreover, rational molecular design enabled boron-π-nitrogen-based PAHs (BπN-PAHs) to be endowed with multiple resonance (MR) effects and exhibit narrowband emission spectra along with high quantum efficiencies; therefore, they could successfully serve as emitters for OLEDs with high color purity. ,,− Nevertheless, because of the intrinsically strong intramolecular charge-transfer (ICT) character in the donor–acceptor (D–A)-based TADF emitters and the large π-conjugation system in the MR emitters, the TADF and MR emitters typically exhibit emissions in the deep-blue to near-infrared regions with dominant peaks above 430 nm. , To the best of our knowledge, no UV emitters have been reported to date among either type of B-PAHs discussed above. A promising strategy for the development of UV emitters involves constructing eligible hybridized local and charge-transfer (HLCT)-type molecules; ,,− these compounds have a local excited (LE) state ensuring a large radiative decay rate from the S 1 to the ground state (S 0 ), along with a wide band gap for short-wavelength emission, and they also possess a charge-transfer (CT) state that facilitates a highly efficient RISC from a higher-lying triplet to S 1 state (hRISC), achieving efficient exciton utilization. Recently, Tang, Zhao, and co-workers empolyed benzonitrile units as acceptors to successfully develop two HLCT emitters, 2BuCz-CNCz and POPCN-2CP; the corresponding doped UV OLEDs achieved high maximum external quantum efficiencies (EQEs) of 10.79 and 8.2% with Commission Internationale de l’Éclairage (CIE) coordinates of (0.161, 0.031) and (0.161, 0.034), respectively.…”

A Breakthrough in Solution‐Processed Ultra‐Deep‐Blue HLCT OLEDs: A Record External Quantum Efficiency Exceeding 10% Based on Novel V‐Shaped Emitters

“…[12] Yan and co-workers reported a novel HLCT emitter 2-(4'-(3-(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)-5phenyl-4H-1,2,4-triazol4-yl)-[1,1'-biphenyl]-4-yl)-1-phenyl-1Hphenanthro[9,10-d] imidazole (PI-TAZ-tbuCZ) with CIE y of 0.043 and EQE max of 6.01% for resultant OLED. [13] Nevertheless, the reported OLED devices were all manufactured by vacuum vapor deposition process, while scarcely any contributions related to efficient solution-processed ultra-deep-blue OLEDs were narrated currently.…”

“…13 C NMR (101 MHz, chloroform-d) 𝛿 (ppm): 167.37, 142.48, 138.36, 132.01, 130.97, 130.81, 129.99, 128.09, 125.81, 123.25, 121.11, 110.61. FTIR (KBr tabletting) 𝜎 (cm −1 ): 3062 (𝜈 Ar─H ), 3043 (𝜈 Ar─H ), 3020 (𝜈 Ar─H ), 1591 (𝜈 C═N ), 1537 (𝜈 C═C (argon, Ar)), 1481 (𝜈 C═C (Ar)), 1448 (𝜈 C═C (Ar)), 1394 (𝜈 C─N ), 1317 (𝜈 C─N ), 1284 (𝜈 C─N ), 1269…”

Simple excited-state modification toward a deep-blue hybridized local and charge-transfer (HLCT) fluorophore and non-doped organic light-emitting diodes

“…40 Our group developed triazole-based blue emitter PI-TAZ-tbuCZ, showing the CIE coordinates of (0.160, 0.043) and an EQE of 6.01% in the doped device. 36 Wang's group reported a pyrene[4,5- d ]imidazole-based emitter 2FPPImTPA, realizing an EQE of 4.12% as well as CIE coordinates of (0.160, 0.038) in a non-doped device. 43 Meanwhile, the pure emitters without doping into host materials usually experience a severe aggregation-caused quenching problem, owing to the ICT effect or close π–π packing interactions.…”

“…This makes HLCT materials possess more advantages than others in developing non-doped blue materials and OLEDs. Until now, various acceptor moieties including imidazole (benzoimidazole, naphthimidazole, phenanthro [9,10-d] imidazole, and pyrene[4,5-d]imidazole), 22,[27][28][29] thiadiazole (benzothiadiazole and naphthothiadiazole), 23,[30][31][32][33] pyrimidine, 34 triazole, [35][36][37] triazine (tris(triazolo)triazine and 2,4-diphenyl-1,3,5-triazine), 21,38 benzonitrile, 39,40 diphenylsulfone, 41 and benzophenone have been used to construct efficient HLCT emitters. Although blue HLCT-OLEDs with a high external quantum efficiency (EQE) exceeding 10% have been achieved, the reported pure deep-blue HLCT materials and non-doped OLEDs with the CIEy r 0.046 are still rare, 42,43 due to the ICT effect and aggregation induced redshift.…”