Liska Tadeas, Swetz Anna, Lai Po-Ni, Zeller Matthias, Teets Thomas S, Gray Thomas G
Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio, 44106, USA.
Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Room 112, Houston, Texas, 77204, USA.
Chemistry. 2020 Jul 8;26(38):8417-8425. doi: 10.1002/chem.202000500. Epub 2020 Jun 24.
The use of organometallic triplet emitters in organic light emitting diodes (OLEDs) is motivated by the premise of efficient intersystem crossing leading to unit internal quantum efficiencies. However, since most devices are based on solid-state components, an inherent limitation to square-planar platinum(II) phosphors is their tendency toward aggregation-based quenching. Here, a new class of emissive, four-coordinate Pt species based on the bisimidazolyl carbazolide (BIMCA) ligand is introduced, which displays highly efficient, long-lived solid-state phosphorescence at room temperature. A set of four BIMCAPt phenyl acetylides were synthesized that emit in the green (λ =507-540 nm) with >60 % quantum yield and millisecond lifetimes. The structures of the resulting species reveal a non-planar structure imposed by steric clashes between BIMCA and the iodo or alkynyl co-ligand. Ground-state and photophysical characterization are presented. Density functional theory calculations indicate that the BIMCA ligand dominates the frontier orbitals along with the first Franck-Condon singlet and triplet excited states.
在有机发光二极管（OLED）中使用有机金属三线态发光体的动机是基于高效系间窜越可实现单位内部量子效率这一前提。然而，由于大多数器件基于固态组件，平面正方形铂（II）磷光体存在一个固有局限性，即它们易于发生基于聚集的淬灭。在此，引入了一类基于双咪唑基咔唑（BIMCA）配体的新型发光四配位铂物种，其在室温下表现出高效、长寿命的固态磷光。合成了一组四种苯乙炔基BIMCAPt，它们在绿色区域（λ = 507 - 540 nm）发射，量子产率>60%，寿命为毫秒级。所得物种的结构揭示了BIMCA与碘或炔基共配体之间的空间位阻导致的非平面结构。给出了基态和光物理表征。密度泛函理论计算表明，BIMCA配体连同第一弗兰克 - 康登单重态和三重态激发态主导前沿轨道。
