Optical properties of a photochromic dye, cis-1,2-dicyano-l,2-bis(2,4,5-tri
methyl-3-thienyl) ethene, have been investigated. Reversible photochromic p
rocess of the dye in solution has been studied, as well as its time evoluti
on properties. Clear photochromism has also been found for the thin films o
f the dye and the growth process of the thin films has been observed by ato
mic force microscopy. (C) 2000 Elsevier Science B.V. All rights reserved.