One‐Step Borylation of 1,3‐Diaryloxybenzenes Towards Efficient Materials for Organic Light‐Emitting Diodes

Abstract

The development of a one-step borylation of 1,3-diaryloxybenzenes, yielding novel boron-containing polycyclic aromatic compounds, is reported. The resulting boron-containing compounds possess high singlet-triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light-emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one-step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron-fused benzo[6]helicene.

Recent progress of green thermally activated delayed fluorescent emitters

“…In the case of the compounds 10 and 11, the steric hindrance between the phenoxaborin acceptor and the phenyl linker induced the distortion of the molecular structure and a strong CT character. A boron-derived 5,9-dioxa-13b-boranaphtho[3,2, 1-de]anthracene acceptor was similar to the phenoxaborin moiety as the acceptor of the TADF emitter, as reported in the photophysical and device data of 10-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10H-phenoxazine (2e) [74].…”

Recent developments in and perspectives on three-coordinate boron materials: a bright future

“…228–231 The highest η EQE of the first TADF-based OLED device using triarylborane 61 as the luminescence layer was ca. 20%, which is comparable to the most efficient PHOLEDs (Scheme 7).…”

Multi‐Resonance Induced Thermally Activated Delayed Fluorophores for Narrowband Green OLEDs

“…It is expected our results would bring a new insight into exploiting novel MR‐TADF materials with full‐color emissions for practical applications. As shown in the Supporting Information, Scheme S1, the MR‐TADF emitters of TCz‐BN, 2F‐BN, 3F‐BN, and 4F‐BN were synthesized from one‐pot borylation of the intermediate products 2–5, and characterized by NMR, mass spectrometry, and elemental analysis …”

“…Interestingly,t he electron-withdrawing units were found to significantly narrow the energy gap for green emission by increasing the ICT character of the aimed molecules whilst maintaining the extremely small FWHMs without compromising the color fidelity,rendering the first-series green MR-TADF emitters to date.Itisexpected our results would bring anew insight into exploiting novel MR-TADF materials with full-color emissions for practical applications.Asshown in the Supporting Information, Scheme S1, the MR-TADF emitters of TCz-BN,2F-BN,3F-BN,and 4F-BN were synthesized from one-pot borylation of the intermediate products 2-5, and characterized by NMR, mass spectrometry,a nd elemental analysis. [6,10] To understand the effect of variation of the skeleton and peripheral units on the geometric and optoelectronic properties,t ime-dependent density functional theory (TD-DFT) using B3LYP(6-31g) method was performed, and the HOMO/ LUMO distributions,e nergy band gaps,a nd oscillator strengths are depicted in Figure 1. Apparently,s imilar multi-resonance induced HOMO-LUMO distribution was also observed for BCz-BN,t hough it has ad ifferent B À Ncontaining skeleton compared with DABNA-1, so that the LUMO is localized on the boron atom as well as its ortho/para positions while the HOMOs are localized on the nitrogen atoms as well as the meta position of boron atom.…”