Refractive Index Change of Dithienylethene in Bulk Amorphous Solid Phase

A diarylethene derivative, 1,2-bis(5-(4-tert-butylphenyl)-2,4-dimethylthiophen-3-yl)- 3,3,4,4,5,5-hexafluorocyclopentene, forms stable amorphous solid with Tg of 68°C. Reversible photochromism in the amorphous solid film is observed upon alternate irradiation with UV (e.g. 313 nm) light and visible (580 nm) light. The refractive index of the solid film changed by as much as 3.8×10-2 along with the photoisomerization.