利用向环金属配体的C—Ir键的对位进行苯基取代这一结构修饰策略,成功合成了两种新型铱(Ⅲ)配合物(3PhNbt)_2Ir(acac)和(3OMePhNbt)_2Ir(acac).相较其橙光发射的母体化合物(Nbt)_2Ir(acac),两个目标化合物的抗结晶性、非晶态热稳定性及溶解性均有显著提高,其磷光发射带也发生了5~10 nm的红移.以(3PhNbt)_2Ir(acac)和(3OMePhNbt)_2Ir(acac)为发光客体材料所制备的单层溶液加工电致红光器件,其最大发光亮度分别为1830 cd·m~(-2)和6630 cd·m~(-2),最大电流效率分别为2.4 cd·A~(-1)和8.7 cd·A~(-1),CIE1931色坐标分别为(0.61,0.39)和(0.62,0.38).相比之下,以母体化合物(Nbt)_2Ir(acac)为发光客体材料所制备的参比器件,其最大发光亮度则为1620 cd·m~(-2),最大电流效率仅为1.5 cd·A~(-1),CIE1931色坐标为(0.59,0.41).上述研究结果表明:向C—Ir键对位进行苯基修饰可以在提高铱(Ⅲ)配合物的可溶液加工性能的同时,获得更为红移的电致发光波长,是一种简单而有效的红光铱(Ⅲ)配合物的分子设计策略.
The exploitation of high-performance solution-processable phosphorescence organic light-emitting diode (PhOLED) materials is of great significance for the realization of large-area, low-cost and flexible display. On the basis of our previous findings that the para-phenylation (phenyl or 4-methoxyphenyl, with respect to the C--Ir bond) on the cyclomet- alated ligand (CAN ligand) of bis[2-phenylbenzothiazolato-N, C2]iridium(Ⅲ)(acetylacetonate) can result in compounds with drastically enhanced film amorphism hence much improved electroluminescence (EL) performance, herein, this para- phenylation strategy was applied to Ir(III) complexes bearing a molecular platform of orange-emissive bis[2-(6-diphenyamin)phenybenzthiazat-NC2']iridium()(acetyacetnate) [(Nbt)2Ir(acac)] to afford two new Ir(Ⅲ) complexes, namely (3PhNbt)zlr(acac) and (3OMePhNbt)2Ir(acac). X-ray diffraction (XRD) characterization results revealed that both the two objective compounds possess much enhanced film amorphism than their parent compound (Nbt)2Ir(acac), validating the efficacy of this para-phenylation strategy in achieving Ir(III) complexes with enhanced film amorphism. Addi- tionally, in comparison with (Nbt)2Ir(acac), both (3PhNbt)zlr(acac) and (3OMePhNbt)2Ir(acac) show much enhanced solubil- ity in common organic solvents, together with 5 10 nm bathochromic-shifled phosphorescence band to red region. As a consequence, (3PhNbt)21r(acac) and (3OMePhNbt)zlr(acac) were expected to be promising guest materials for the fabrication of high-performance solution-processed red PhOLEDs. EL characterization results indicated that for single-layer red solu- tion-processed PhOLEDs using (3PhNbt)2Ir(acac) and (3OMePhNbt)2Ir(acac) as the guest dopant, they show peak current efficiency of 2.4 cd-A- and 8.7 cd.A-, maximum brightness of 1830 cdm-2 and 6630 cdm-2, and CIE coordinates of (0.61, 0.39) and (0.62, 0.