Hofbeck Thomas, Niehaus Thomas A, Fleck Michel, Monkowius Uwe, Yersin Hartmut
Institut für Physikalische Chemie, Universität Regensburg, D-93053 Regensburg, Germany.
Institut Lumière Matière, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, F-69622 Villeurbanne, France.
Molecules. 2021 Jun 4;26(11):3415. doi: 10.3390/molecules26113415.
We present an overview over eight brightly luminescent Cu(I) dimers of the type CuX(P∩N) with X = Cl, Br, I and P∩N = 2-diphenylphosphino-pyridine (PhPpy), 2-diphenylphosphino-pyrimidine (PhPpym), 1-diphenylphosphino-isoquinoline (PhPiqn) including three new crystal structures (CuBr(PhPpy) , CuI(PhPpym) and CuI(PhPiqn) ). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time and quantum yield vary over large ranges. For deeper characterization, we select CuI(PhPpy), , showing a quantum yield of 81%. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S and triplet T states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S-T) = 380 cm (47 meV), a transition rate of k(S→S) = 2.25 × 10 s (445 ns), T zero-field splittings, transition rates from the triplet substates and spin-lattice relaxation times. We also discuss the interplay of S-TADF and T-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.
我们概述了八种发光明亮的Cu(I)二聚体，其类型为CuX(P∩N)，其中X = Cl、Br、I，P∩N = 2 - 二苯基膦基吡啶(PhPpy)、2 - 二苯基膦基嘧啶(PhPpym)、1 - 二苯基膦基异喹啉(PhPiqn)，包括三种新的晶体结构（CuBr(PhPpy)、CuI(PhPpym)和CuI(PhPiqn)）。然而，我们主要关注它们的光致发光特性。所有化合物在室温下均表现出热激活延迟荧光(TADF)和磷光的组合。发射颜色、衰减时间和量子产率在很大范围内变化。为了进行更深入的表征，我们选择了量子产率为81%的CuI(PhPpy)。DFT和SOC - TDDFT计算深入了解了单重态S和三重态T态的电子结构。两者均源于金属 + 碘化物到配体的电荷转移跃迁。对1.2 ≤ T ≤ 300 K测量的发射衰减动力学进行评估，得出∆E(S - T) = 380 cm⁻¹(47 meV)，k(S→S) = 2.25 × 10⁶ s⁻¹(445 ns)的跃迁速率、T零场分裂、来自三重态亚态的跃迁速率和自旋 - 晶格弛豫时间。我们还讨论了S - TADF和T - 磷光的相互作用。组合的发射路径缩短了整体衰减时间。对于OLED应用，利用单重态和三重态的捕获都可能对提高器件性能非常有利。
