第三代利用熱活化型延遲螢光 (thermally activated delayed fluorescence, TADF) 材料的 OLED,使用低成本的有機化合物即可有高放光效率,同時突破第一代螢光材料 OLED 效率的限制及第二代磷光材料 OLED 使用貴金屬而導致高成本的問題,在近年來備受矚目。 本論文以硼為中心原子,搭配 pyridyl pyrrolide 雙牙配位基為 electron acceptor 及兩個具有立體障礙的 carbazole 或 triphenylamine 當作 electron donor 配位基,希望利用四配位硼錯合物的四面體結構,將 HOMO 與 LUMO 形成正交狀態,降低 ΔEST 而具有 TADF 效應。利用光物理量測、電化學量測及理論計算等相關研究,探討這一系列硼錯合物的關係,並進行元件製作,得到最大外部量子效率達 13.5% 的元件結果。
A series of novel boron complexes with electron deficient pyridyl pyrrolide and electron donating triphenylamine or phenylcarbazolyl fragment were synthesized. In this thesis, we strategically design the titled ligands such that the electron donor (HOMO) and acceptor (LUMO) moieties are spatially separated with orthogonal orientation. The slim orbital overlap between HOMO and LUMO leads to the close lying S1 and T1 states and thereby the generation of thermally activated delayed fluorescence (TADF). OLEDs using complex 2a processed by spin coating achieved an external quantum efficiency of 13.5%, demonstrating high performance boron-core based OLEDs via harvesting TADF.