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

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.     

Hybrid Metal Halides with Multiple Photoluminescence Centers

Very little is known about the realm of solid‐state metal halide compounds comprising two or more halometalate anions. Such compounds would be of great interest if their optical and electronic properties could be rationally designed. Herein, we report a new example of metal halide cluster‐assembled compound (C₉NH₂₀)₉[Pb₃Br₁₁](MnBr₄)₂, featuring distinctly different anionic polyhedra, namely, a rare lead halide cluster [Pb₃Br₁₁]^5? and [MnBr₄]^2?. In accordance with its multinary zero‐dimensional (0D) structure, this compound is found to contain two distinct emission centers, 565 nm and 528 nm, resulting from the formation of self‐trapped excitons and ⁴T₁‐⁶A₁ transition of Mn²⁺ ions, respectively. Based on the high durability of (C₉NH₂₀)₉[Pb₃Br₁₁](MnBr₄)₂ upon light and heat, as well as high photoluminescence quantum yield (PLQY) of 49.8 % under 450 nm blue light excitation, white light‐emitting diodes (WLEDs) are fabricated, showcasing its potential in backlight application.     

Combining Charge‐Transfer Pathways to Achieve Unique Thermally Activated Delayed Fluorescence Emitters for High‐Performance Solution‐Processed,Non‐doped Blue OLEDs

Two efficient blue thermally activated delayed fluorescence compounds, B‐oCz and B‐oTC , composed of ortho‐donor (D)–acceptor (A) arrangement were designed and synthesized. The significant intramolecular D–A interactions induce a combined charge transfer pathway and thus achieve small ΔE _ST and high efficiencies. The concentration quenching can be effectively inhibited in films of these compounds. The blue non‐doped organic light emitting diodes (OLEDs) based on B‐oTC prepared from solution processes shows record‐high external quantum efficiency (EQE) of 19.1 %.