Jouaiti Abdelaziz, Ballerini Lavinia, Shen Hsiang-Ling, Viel Ronan, Polo Federico, Kyritsakas Nathalie, Haacke Stefan, Huang Yu-Ting, Lu Chin-Wei, Gourlaouen Christophe, Su Hai-Ching, Mauro Matteo
Laboratoire de Synthèse et Fonctions des Architectures Moléculaires, UMR7140 Chimie de la Matiere Complexe, Université de Strasbourg & CNRS, 4 rue Blaise, Pascal, 67000, Strasbourg, France.
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR7504, Université de Strasbourg & CNRS, 23 rue du Loess, 67083, Strasbourg, France.
Angew Chem Int Ed Engl. 2023 Sep 18;62(38):e202305569. doi: 10.1002/anie.202305569. Epub 2023 Jul 17.
Two binuclear heteroleptic Cu complexes, namely Cu-NIR1 and Cu-NIR2, bearing rigid chelating diphosphines and π-conjugated 2,5-di(pyridin-2-yl)thiazolo[5,4-d]thiazole as the bis-bidentate ligand are presented. The proposed dinuclearization strategy yields a large bathochromic shift of the emission when compared to the mononuclear counterparts (M1-M2) and enables shifting luminescence into the near-infrared (NIR) region in both solution and solid state, showing emission maximum at ca. 750 and 712 nm, respectively. The radiative process is assigned to an excited state with triplet metal-to-ligand charge transfer ( MLCT) character as demonstrated by in-depth photophysical and computational investigation. Noteworthy, X-ray analysis of the binuclear complexes unravels two interligand π-π-stacking interactions yielding a doubly locked structure that disfavours flattening of the tetrahedral coordination around the Cu centre in the excited state and maintain enhanced NIR luminescence. No such interaction is present in M1-M2. These findings prompt the successful use of Cu-NIR1 and Cu-NIR2 in NIR light-emitting electrochemical cells (LECs), which display electroluminescence maximum up to 756 nm and peak external quantum efficiency (EQE) of 0.43 %. Their suitability for the fabrication of white-emitting LECs is also demonstrated. To the best of our knowledge, these are the first examples of NIR electroluminescent devices based on earth-abundant Cu emitters.
本文介绍了两种双核杂配铜配合物，即Cu-NIR1和Cu-NIR2，它们带有刚性螯合二膦和π共轭的2,5-二（吡啶-2-基）噻唑并[5,4-d]噻唑作为双齿配体。与单核类似物（M1-M2）相比，所提出的双核化策略使发射产生了较大的红移，并使溶液和固态中的发光都能转移到近红外（NIR）区域，分别在约750和712 nm处显示最大发射。深入的光物理和计算研究表明，辐射过程归因于具有三重态金属到配体电荷转移（MLCT）特征的激发态。值得注意的是，双核配合物的X射线分析揭示了两种配体间的π-π堆积相互作用，产生了一种双锁定结构，该结构不利于激发态下Cu中心周围四面体配位的扁平化，并保持增强的近红外发光。M1-M2中不存在这种相互作用。这些发现促使Cu-NIR1和Cu-NIR2成功应用于近红外发光电化学电池（LEC），其电致发光最大值可达756 nm，峰值外量子效率（EQE）为0.43%。还证明了它们适用于制造发白光的LEC。据我们所知，这些是基于储量丰富的铜发光体的近红外电致发光器件的首个实例。
