双层有机电致发光器件中的激基复合物发射及特性

Exciplex Emissions and Properties in Bilayer Organic Electroluminescent Diodes

以两种常用的芳香二胺TPD和NPB为空穴传输材料 (HTM)和BBOT为电子传输材料组成双层器件 ,获得了相对于组成材料的荧光光谱红移和宽化的电致发光 .用光致发光表征了这种发射来自激基复合物 ,并用器件的能级图说明激基复合物的类型为BBOT的激发态BBOT 与基态的HTM相互作用的复合物 .比较TPD和NPB的分子结构和能级表明 ,分子具有有利的构型和取向比合适的能级更容易形成激基复合物 .

The bilayer organic electroluminescent diodes using two common aromatic diamines TPD (N, N'-diphenyl-N, N'-bis(3-methylphenyl)-1, 1'-biphenyl-4,4'-diamine) and NPB (N, N'-bis(1-naphthyl)-N, N'-diphenyl-(1, 1'-biphenyl)-4,4'-diamine) as hole transporting materials (HTM) and BBOT (2,5-bis(5-tert-butyl-2-benzoxazolyl)-thiophene) as electron transporting material have been fabricated. Redshifted and broad electroluminescent spectra relative to the fluorescent spectra of constituent materials were obtained. This electroluminescence was originated mainly from exciplexes evidenced by photoluminescence measurements, and the type of which were interpreted as the complex formed by the interaction between the excited state of BBOT (BBOT*) and ground state of the HTM in terms of the energy level diagram of the bilayer devices. By comparing the molecular structures and energy levels of TPD and NPB, it is demonstrated that exciplex formation can more easily take place for a molecule with favorable geometry and orientation than the one with appropriate energy level.