Strategies for highly luminescent d10 coinage metal compounds challenging PtII- and IrIII-based emitters

挑战 PtII 和 IrIII 发射体的高发光 d10 造币金属化合物的策略

• 批准号: 195201394
• 负责人: Professor Dr. Andreas Steffen
• 金额: --
• 依托单位: Lehrstuhl für Anorganische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/195201394?language=en
• 关键词: Strategies; highly; luminescent; d10; coinage

Our preliminary results have shown that non-traditional carbene ligands, such as CAACs, can act as exceptionally potent pi-chromophore ligands, leading to very high radiative rate constants, which is a prerequisite for high quantum yields and application of transition metal complexes in OLEDs or as NIR single photon sources. Furthermore, we have shown that dispersive interactions between d10 metal centers as well as between ligands can also have a beneficial influence on the excited state properties. However, a detailed structure-property relationship is still missing, although we have formulated first design principles, which is mandatory prior to applying d10 coinage metal complexes bearing such types of ligands or such dispersive interactions. We thus aim at a) exploiting exceptional pi-acceptor carbenes for enhancing spin-orbit coupling (SOC), and b) a deep understanding of the influence of metal-metal interactions on the photophysical properties of the excited states, both of which are necessary in order to fully control the properties and to be able to design materials for a given application.In most of the T1 and TADF emitters based on d10 coinage metal complexes both absorption S0-S1 and emission T1-S0 are dominated by an overlap and symmetry forbidden HOMO-LUMO transition, with the HOMO being of Cu(d-sigma) and the LUMO of ligand(pi*) character. As SOC can only occur between triplet and singlet states which differ in one and only one M(d) orbital, phosphorescence is ensured only by coupling of the triplet excited state T1 with 1MLCT states of reasonable oscillator strength Sn-S0, which are usually energetically very high lying, limiting the radiative rate constant k(r). By either raising the energy of the M(d) orbitals of pi symmetry with respect to the carbene centered LUMO, or by decreasing the energy of the M(d-sigma) orbital below the M(d-pi) we will be able to decrease the energy gap between T1 and those 1MLCT states with a high transition dipole moment coupling them with the ground state S0. We will work out the design criteria for pure T1 emitters in the blue, and TADF emission in the red to near-IR. Suitable candidates will be exploited in devices as well as time-correlated single photon sources.Metallophilic interactions pre-designed in the ground state allow both metals to participate in the excited state and have a great influence on the radiative rate constants for T1 emission as well as for TADF. Also, intra- and intermolecular pi-stacking of the chromophore ligands can drastically alter the photophysical properties of a given system. We aim to explore these concepts further to I) be able to design emitter materials for a given application and II) generate stimuli-responsive photoactive materials.

我们的初步结果表明，非传统的卡宾配体，如CAAC，可以作为非常有效的π-发色团配体，导致非常高的辐射速率常数，这是高量子产率和过渡金属配合物在OLED中的应用或作为NIR单光子源的先决条件。此外，我们已经表明，d10金属中心之间以及配体之间的色散相互作用也可以对激发态性质产生有益的影响。然而，一个详细的结构-性能的关系仍然是失踪，虽然我们已经制定了第一设计原则，这是强制性的应用d10钴金属配合物轴承这种类型的配体或分散的相互作用之前。因此，我们的目标是a）利用特殊的pi受体卡宾来增强自旋轨道耦合（SOC），以及B）深入了解金属-金属相互作用对激发态光物理性质的影响，为了完全控制性能和能够设计用于给定应用的材料，这两者都是必需的。配合物的吸收S 0-S1和发射T1-S 0都由重叠和对称禁戒的HOMO-LUMO跃迁控制，HOMO具有Cu（d-σ）特征，LUMO具有配体（π *）特征。由于SOC只能发生在三重态和单重态之间，它们在一个且仅一个M（d）轨道上不同，磷光只能通过三重激发态T1与合理振子强度Sn-S 0的1 MLCT态的耦合来确保，这些振子强度通常在能量上非常高，限制了辐射速率常数k（r）。通过提高π对称的M（d）轨道相对于卡宾中心LUMO的能量，或者通过降低M（d-sigma）轨道的能量低于M（d-pi），我们将能够减小T1和具有高跃迁偶极矩的那些1 MLCT态之间的能隙，这些1 MLCT态将它们与基态S 0耦合。我们将制定出纯T1发射体在蓝色和TADF发射在红色到近红外的设计准则。合适的候选人将在设备以及时间相关的单光子源中开发。在基态预先设计的亲金属相互作用允许两种金属参与激发态，并对T1发射以及TADF的辐射速率常数有很大的影响。此外，发色团配体的分子内和分子间π-堆叠可以极大地改变给定系统的光物理性质。我们的目标是进一步探索这些概念，以I）能够为给定的应用设计发射器材料，II）生成刺激响应的光敏材料。