1158841-79-2

Upstream product

• 1146340-38-6 1-phenyl-2-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl]-1H-benzo[d]imidazole 
• 202831-65-0 (4'-bromobiphenyl-4-yl)-diphenylamine 
• 2620-76-0 2-(4-bromophenyl)-1-phenyl-1H-benzimidazole 

Relevant academic research and scientific papers

Highly efficient and solution-processed iridium complex for single-layer yellow electrophosphorescent diodes

A novel electrophosphorescent material based on a biscyclometalated iridium(iii) complex of the N,N-diphenyl-4′′-(1-phenyl-1H-benzo[d] imidazol-2-yl)-[1,1′:4′,1′′-terphenyl]-4-amine ligand, named Ir(TPABPBI)2(acac), has been synthesized and its application in organic light emitting devices (OLEDs) was studied. Highly efficient, solution-processed, single-layer, electrophosphorescent diodes utilizing the complex have been prepared and characterized. In these devices, the high triplet energy poly(9-vinylcarbazole) (PVK) is used as a host polymer doped with 2-(4-biphenylyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) employed for electron transport. When the doping concentration of Ir(TPABPBI) 2(acac) is up to 4%, devices with a current efficiency of 30.0 cd A-1 corresponding to an EQE of 15% can thus be achieved, along with the Commission de l'Eclairage 1931 chromaticity coordinates of (0.507, 0.486). More importantly, the yellow phosphorescence can be achieved without the generation of excimer emission. Such devices exhibit a very broad and featureless peak at ca. 568 nm with a wide full spectral width at half maximum (FWHM) of 83 nm. These results render Ir(TPABPBI)2(acac) a promising organic phosphor for applications in yellow OLEDs, especially for large-area, highly efficient and cheap yellow PhOLEDs.

Terphenyl backbone-based donor-π-acceptor dyads: Geometric isomer effects on intramolecular charge transfer

The molecular geometry effects of ortho, meta, and para-terphenyl based donor-π-acceptor (D-π-A) dyads on intramolecular charge transfer (ICT) were studied to investigate structure-ICT relationships. Terphenyl based D-π-A dyads were prepared by two-step palladium catalyzed, Suzuki-Miyaura coupling reactions, in which triphenylamine (TPA) was used as the electron donor and 1,2-diphenyl-benzimidazole (IMI) as the electron acceptor. The photophysical and electrochemical properties of terphenyl backbone-based ortho (O), meta (M), and para (P) dyads were compared. In steady state absorption spectra, a red-shift of CT band was observed in the order O M P, which was attributed to terphenyl isomer conjugation effects and agreed well with density functional theory (DFT) based calculations. In particular, the emission spectra of the three terphenyl D-π-A dyads produced showed similar emission maxima at ～475 nm and a bathochromic shift property was observed in order to increase the solvent polarity, indicating the ICT process. From Lippert-Mataga plots, excited-state dipole moment changes (Δμ) were estimated to be 31.5 Debye (D) for O, 62.9 D for M, and 51.5 D for P. For M isomer, a large Δμ and the markedly reduced quantum yield was shown, as well as photo-induced electron transfer (PET) was expected in the excited state, but no radical species were observed by femtosecond transient absorption (TA) measurements. Based on experimental results, we conclude that all three terphenyl based D-π-A dyads, including non-conjugated ortho- and meta-terphenyl dyads, exhibit partial charge transfer rather than unit-electron transfer.

Enhanced efficiency in nondoped, blue organic light-emitting diodes utilizing simultaneously local excition and two charge-transfer exciton from benzimidazole-based donor-acceptor molecules

The simultaneous utilization of all charge-transfer excitons and local excitons is the pathway to obtain the high efficiency fluorescent organic light-emitting diodes (FOLEDs). Here, a twisted intramolecular charge transfer state (TICT-state), a planar intramolecular charge transfer state (ICT-state), and a locally excited state (LE-state) are demonstrated to enhance the occurrence of singlet excitons in the fluorescent emitters, which are based on benzimidazole and triphenylamine donor-acceptor derivatives. The synthesis, photophysics and electroluminescent (EL) performance are studied systematically. The fluorescence emitters (TPABBBI and TPABBI) with the special TICT and ICT characteristics realize the electron-hole (e-h) recombination via intramolecular conversion from charge-transfer excitons to radiative singlet exciton. The devices based on them show high efficiency (5.1 cd/A, 5.77 lm/W, 5.66% of EQEm for TPABBBI and 3.56 cd/A, 3.11 lm/W, 4.23% for TPABBI), low efficiency roll-off at high luminance and stable blue emission.