杂配体铱(III)配合物磷光材料降解现象的理论研究

The development and application of phosphorescent emitters in organic light-emitting diodes (OLEDs) have played a critical role in the push to commercialization of OLED-based display and lighting technologies. Up to now, the efficiency and lifetime of stable red, green and blue-green light emitting devices have been improved remarkably and can fulfill the application requirements, but the low efficiency and short lifetime of blue emitting devices is still the major limitation for improving the efficiency of such devices. Thereby, the improvement of their photostability is very import for a broad application of blue phosphors in this promising technology. However, the degradation phenomenon in blue phosphsors has not be realized. Iridium (III) complexes, in particular, are prime candidates for highly-efficient blue-emissive dopants in OLEDs because of their thermal stabilities, adequate triplet lifetimes, and strong spin-orbit coupling effects. For better understanding the degradation process of the phosphorescent emitters in OLEDs, here, we use density functional theory methods to study the electronic, photophysical and photochemical properties of a series of iridium (III) complexes, theoretically.

磷光材料的开发在OLED显示与发光技术市场化的发展中起着至关重要的推动作用。目前，红色、绿色以及蓝绿色磷光材料的效率、寿命以及稳定性已经有了很大的进展。然而，高效率、高稳定性的蓝色磷光材料却非常缺乏，成为目前阻碍OLED照明器件效率提高的主要技术难点。因此蓝色磷光材料的光化学稳定性（即降解反应）的研究已成为该领域主要的攻关方向之一。铱(III)配合物具有很好的跃迁能隙、热稳定性、激发态寿命，以及很强的自旋耦合能力，是OLED有机发光器件中主要的蓝色磷光备选材料。为更好地了解OLED器件中客体磷光材料的降解现象，这里，我们将利用量子计算化学方法从理论角度对一系列过渡金属铱(III)配合物的光化学稳定性做详细研究分析。

目前，高效率、高稳定性的蓝色磷光材料非常缺乏，是阻碍OLED 照明器件效率提高的主要技术难点。铱，铂，钌，铼以及锇等过渡金属配合物具有很好的热稳定性，激发态寿命以及很强的自旋耦合能力，是蓝色磷光主要的备选材料之一。本研究利用DFT理论计算并结合UV-Vis实验测定，检测了一系列过渡金属铱(III)络合物前线轨道HOMO/LUMO 的能量、分布状态、能隙值；吸收、发射光的波长和能量；光化学降解反应所涉及的降解路线、能垒、反应热和降解产物等信息。探讨了环铱金属配位基的选择和修饰对其电子、光物理、光化学性质的影响，建立了配位基的选择和修饰与络合物磷光颜色以及光化学稳定性之间的内在关系，希望我们的结果可以为过渡金属铱络合物蓝色磷光材料的设计开发提供有益的理论依据。