Electroluminescence and laser emission of soluble pure red fluorescent molecular glasses based on dithienylbenzothiadiazole

Soluble molecular red emitters la/lb are synthesized by Stille coupling from 2-(3,5-di(l-naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610 nm in CH2Cl2 solution and 620 nm in solid films. Replacing the n-hexyl substituent by 4-sec-butoxyphenyl produces a marked increase of glass transition temperature (Tg) from 82 °C to 137 °C and increases the solubility in toluene and p-xylene, thus improving the filmforming properties. Cyclic voltam metry shows that the compounds can be reversibly oxidized and reduced around +1.10 and -1.20V, respectively. A two-layered electroluminescent device based on lb produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1 cd A-1. Furthermore, when used as a solution-processed red emitter in optically pumped laser devices, compound lb successfully produces a lasing emission at ca. 650 nm. © 2009 WILEY-VCH Verlag GmbH & Co. KCaA.