Organic Materials Laboratory, Department of Chemistry, Indian Institute of Technology Roorkee , Roorkee 247667, India.
Department of Material Science and Engineering, National Tsing Hua University , Hsinchu 30013, Taiwan.
J Org Chem. 2017 Nov 3;82(21):11512-11523. doi: 10.1021/acs.joc.7b02127.
New benzothiadiazole-based materials containing methyl substitution are prepared and characterized as promising green/yellowish green emitters for electroluminescent applications. The dyes exhibited shorter wavelength absorption and emission when compared to nonmethylated dyes. A dye containing methyl group on the donor side exhibited blue shift in absorption and emission when compared to the analogous dye containing methyl group away from donor. The steric effect exerted by the methyl group is responsible for the nonplanar arrangement of donor and acceptor, which inhibited the intramolecular charge transfer. All the dyes displayed solvatochromism in the emission spectra characteristic of hybridization of local and charge transfer excited states. Due to the benefit of methyl group, the dyes restrained the formation of aggregates in the solid state. Solution processed multilayered OLED device were fabricated employing these compounds either as host emitters or dopant emitters in suitable host matrix and exhibited green/yellowish green electroluminescence with external quantum efficiency as high as 4.6% (15.7 cd A).
新型含甲基取代基的苯并噻二唑类材料被制备并被表征为有前途的绿色/黄绿色电致发光应用的发光体。与非甲基化染料相比，这些染料具有较短的波长吸收和发射。与供体侧含有甲基的类似染料相比，供体侧含有甲基的染料在吸收和发射时表现出蓝移。供体和受体的非平面排列抑制了分子内电荷转移，这是由甲基施加的空间位阻效应造成的。所有染料在发射光谱中都表现出溶剂化效应，这是局部和电荷转移激发态杂化的特征。由于甲基的存在，这些染料在固态中抑制了聚集的形成。采用这些化合物作为主体发光体或掺杂剂发光体，在合适的主体基质中，通过溶液处理制备了多层 OLED 器件，显示出绿色/黄绿色电致发光，外量子效率高达 4.6%（15.7 cd A）。
