Synthesis, characterization, and electrogenerated chemiluminescence of phenyl-substituted, phenyl-annulated, and spirofluorenyl-bridged oligothiophenes
作者:Ullrich Mitschke、Peter Bäuerle
DOI:10.1039/b006553f
日期:——
To overcome the insolubility of higher oligothiophenes and simultaneously to enhance their processability with respect to an application in molecularly doped organic light-emitting devices (OLEDs) we synthesized phenyl-substituted, phenyl-annulated, and spirofluorenyl-bridged oligothiophenes 1–5. Significantly improved solubilities in polar solvents of up to three orders of magnitude were found and their optical and electrochemical properties were investigated in solution. Reflecting small conformational changes and the almost complete electronic separation of the substituents, phenyl substitution and the introduction of a spiro core by bridging the central bithienyl unit only slightly affected optical and redox properties in comparison to the unmodified oligothiophenes (6–8). In contrast, the presence of an isothianaphthene (benzo[c]thiophene) unit in the oligomeric chain led to a distinct approximation of the frontier orbitals and consequently to a red-shift of both absorption and fluorescence. Finally, we demonstrated the applicability of some oligomers as dopants for OLEDs by electrogenerated chemiluminescence (ECL).
为了克服高阶寡聚噻吩的不溶性并同时提高它们在分子掺杂有机发光二极管(OLEDs)应用中的可加工性,我们合成了苯基取代的、苯基稠合的和螺芴基桥连的寡聚噻吩1-5。研究发现这些化合物在极性溶剂中的溶解度显著提高了最多三个数量级,并对它们在溶液中的光学和电化学性质进行了研究。与未修饰的寡聚噻吩(6-8)相比,苯基取代和通过桥连中心联噻吩基团引入螺环核心仅略微影响了光学和氧化还原性质,这反映了构象的微小变化和取代基之间几乎完全的电子分离。相比之下,寡聚物链中异噻萘(苯并[c]噻吩)单元的存在导致前沿轨道的明显趋近,因此吸收和荧光都发生红移。最后,我们通过电化学发光(ECL)证明了某些寡聚物作为OLED掺杂剂的适用性。