Beresneviciute Raminta, Kumar Anil, Blazevicius Dovydas, Lenka Sushanta, Hsieh Song-Ting, Tsai Ming-Feng, Krucaite Gintare, Tavgeniene Daiva, Jou Jwo-Huei, Grigalevicius Saulius
Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT50254 Kaunas, Lithuania.
Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Rd., Hsinchu 30013, Taiwan.
Molecules. 2025 Apr 25;30(9):1911. doi: 10.3390/molecules30091911.
Here, we present two series of new electroactive compounds containing electron donors (carbazolyl) and electron acceptor (pyridinyl) fragments as potential host materials. The objective compounds 9-(2-ethylhexyl)-3,6-di [3-(methoxypyridin-3-yl)carbazol-9-yl]carbazoles and were synthesized by an Ullmann coupling reaction between the intermediate derivatives: 9-(2-ethylhexyl)-3,6-diiodocarbazole and corresponding 3-(methoxypyridin-3-yl)-9-carbazole. Other target derivatives, 9-alkyl-3-[-(9-alkylcarbazol-3-yl)--(4-methylpyridin-2-yl)amino]carbazoles and , were also prepared, according to the Ullmann reaction method, from 2-amino-4-methylpyridine and the corresponding 3-iodo-9-alkylcarbazole. Thermogravimetric analysis confirmed that the new derivatives are highly thermally stable compounds, with 5% weight loss in the temperature range of 349 °C to 488 °C. According to differential scanning calorimetry results, some amorphous materials exhibit very high glass transition temperatures exceeding 150 °C in some cases, which is a significant advantage for compounds with potential applications in organic light-emitting devices. The electroluminescent properties of devices utilizing the new hosts or with 5.0, 10.0, 15.0, and 20.0 wt.% concentrations of the dopant tris(2-phenylpyridine)iridium(III), Ir(ppy), were demonstrated. All the PhOLEDs emitted light at approximately 515 nm with CIE coordinates of (0.30, 0.61) due to Ir(ppy) emissions. The most efficient device with host demonstrated a maximum power efficacy of 8.0 lm/W, maximum current efficiency of 12.7 cd/A, and maximal external quantum efficiency of 5.4% with a relatively low turn-on voltage of 4.3 eV, as well as luminance exceeding 4000 cd/m. Additionally, 15 wt.% Ir(ppy) emitter-based PhOLED with host outperformed the other devices by displaying a maximum power efficacy of 9.6 lm/W, maximum current efficiency of 16.0 cd/A, and maximal external quantum efficiency of 6.7% with a relatively low turn-on voltage of 3.7 eV, as well as luminance reaching 11,200 cd/m. Some devices seem to exhibit higher efficiencies than those previously reported for OLEDs that utilize a 4,4'-bis(9-carbazolyl)-2,2'-biphenyl (CBP) host.
在此，我们展示了两类新型电活性化合物，它们含有电子供体（咔唑基）和电子受体（吡啶基）片段，作为潜在的主体材料。目标化合物9-(2-乙基己基)-3,6-二[3-(甲氧基吡啶-3-基)咔唑-9-基]咔唑是通过中间体衍生物9-(2-乙基己基)-3,6-二碘咔唑与相应的3-(甲氧基吡啶-3-基)-9-咔唑之间的乌尔曼偶联反应合成的。其他目标衍生物9-烷基-3-[-(9-烷基咔唑-3-基)--(4-甲基吡啶-2-基)氨基]咔唑也是根据乌尔曼反应方法，由2-氨基-4-甲基吡啶和相应的3-碘-9-烷基咔唑制备而成。热重分析证实，这些新衍生物是热稳定性很高的化合物，在349℃至488℃的温度范围内失重5%。根据差示扫描量热法结果，一些非晶态材料在某些情况下表现出非常高的玻璃化转变温度，超过150℃，这对于在有机发光器件中具有潜在应用的化合物来说是一个显著优势。展示了使用新型主体或掺杂浓度为5.0、10.0、15.0和20.0 wt.%的掺杂剂三(2-苯基吡啶)铱(III)（Ir(ppy)）的器件的电致发光特性。由于Ir(ppy)的发射，所有的磷光有机发光二极管在约515 nm处发光，CIE坐标为(0.30, 0.61)。使用主体的最有效器件表现出最大功率效率为8.0 lm/W、最大电流效率为12.7 cd/A、最大外量子效率为5.4%，开启电压相对较低，为4.3 eV，亮度超过4000 cd/m²。此外，基于15 wt.% Ir(ppy)发射体的使用主体的磷光有机发光二极管表现优于其他器件，其最大功率效率为9.6 lm/W、最大电流效率为16.0 cd/A、最大外量子效率为6.7%，开启电压相对较低，为3.7 eV，亮度达到11200 cd/m²。一些器件似乎表现出比先前报道的使用4,4'-双(9-咔唑基)-2,2'-联苯（CBP）主体的有机发光二极管更高的效率。
