Structure-dependent fluorescence in sexithiophene single crystals

Sexithiophene (6T) is a promising material for organic-based electronic devices and its photoluminescence spectra remain a topic of interest. 6T exhibits two different crystal forms, for which photoluminescence spectra and stimulated emission were measured at various temperatures. The authors observe a strong dependence of the spectra on crystal structure. Precise determination of the electronic transitions of both structures shows that most of the steady-state photoluminescence arises from crystal defects.