A series of carbazole-containing tetraarylsilane compounds, namely p-BISiPCz (1), m-BISiPCz (2), p-OXDSiPCz (3) and m-OXDSiPCz (4) were designed and synthesized by incorporating electron-donating carbazole and electron-accepting benzimidazole or oxadiazole into one molecule via a silicon-bridge linkage mode. Their thermal, photophysical and electrochemical properties can be finely tuned through the different groups and linking topologies. The di-para-position compounds 1 and 3 display higher glass transition temperatures and slightly lower triplet energies than their di-meta-position isomers 2 and 4, respectively. The four compounds exhibit similar HOMO levels (5.60–5.63 eV), while the LUMO level of 3 (2.36 eV) is slightly lower than that of 4 (2.28 eV). The silicon-interrupted conjugation of the electron-donating and electron-accepting segments endows these materials with relative high triplet energies, good thermal and morphological stability, and bipolar transporting ability. For FIrpic-based blue PhOLEDs, the di-meta-position compounds 2 and 4 display better device performances than their di-para-position analogues 1 and 3, respectively. Device B using 2 as the host exhibits the best performance with a maximum current efficiency of 29.3 cd A−1, a maximum power efficiency of 19.8 lm W−1, and a maximum external quantum efficiency of 11.4%. Green phosphorescent devices using (ppy)2Ir(acac) as guest and 1–4 as hosts show excellent EL performances with maximum external quantum efficiencies of 18.3–22.2%. Remarkably, device H hosted by 4 still exhibits an external quantum efficiency of 19.4% at the extremely high luminance of 10 000 cd m−2. These efficiencies are significantly higher than those of blue and green control devices using mCP as host, respectively.
通过
硅桥连接模式将电子供体
咔唑和电子受体
苯并咪唑或噁二唑结合到一个分子中,设计并合成了一系列含
咔唑的四芳基
硅烷化合物,即 p-BISi
PCz(1)、m-BISi
PCz(2)、p-OXDSi
PCz(3)和 m-OXDSi
PCz(4)。它们的热学、光物理和电
化学特性可通过不同的基团和连接拓扑结构进行微调。与二元位异构体 2 和 4 相比,二元位化合物 1 和 3 的
玻璃化温度更高,三重能略低。四种化合物表现出相似的 HO
MO 水平(5.60-5.63 eV),而 3 的 LU
MO 水平(2.36 eV)略低于 4(2.28 eV)。这些材料的供电子段和受电子段的
硅间断共轭赋予了它们相对较高的三重态能量、良好的热稳定性和形貌稳定性以及双极传输能力。对于基于 FIrpic 的蓝色 PhOLED,二元位化合物 2 和 4 的器件性能分别优于其二元位类似物 1 和 3。使用 2 作为宿主的器件 B 性能最佳,其最大电流效率为 29.3 cd
A-1,最大功率效率为 19.8 lm W-1,最大外部量子效率为 11.4%。以 (ppy)2Ir(acac) 为客体、1-4 为宿主的绿色
磷光器件显示出卓越的电致发光性能,最大外部量子效率为 18.3-22.2%。值得注意的是,以 4 为宿主的器件 H 在 10 000 cd m-2 的超高亮度下仍能表现出 19.4% 的外部量子效率。这些效率分别明显高于使用 m
CP 作为宿主的蓝色和绿色控制器件。