Refractive Index Measurements of Weil-Defined Polygon Crystals of Thiophene/Phenylene Co-Oligomers

摘要

We have improved the crystal growth methods of thiophene/phenylene co-oligomers (TPCOs). The crystal growth was carried out in a liquid phase. The resulting crystals were well defined in thin polygons with several pairs of parallel crystal faces that function as optical mirrors. This produces interference fringes in the emission and reflectance spectra, enabling us to determine the anisotropic refractive indices. From among TPCOs we chose 5,5'-bis(4-biphenylyl)-2,2'-bithiophene (BP2T) and its methoxy derivative 5,5'-bis(4'-methoxybiphenyl-4-yl)-2,2'-bithiophene (BP2T-OMe),