Optical properties of photochromic dyes in the amorphous state

• Published in: Japanese Journal of Applied Physics Vol. 36; no. 6A; pp. 3736 - 3739
• Main Authors: KANEUCHI, Y, KAWAI, T, HAMAGUCHI, M, YOSHINO, K, IRIE, M
• Format: Journal Article
• Language: English
• Published: Tokyo Japanese journal of applied physics 01.06.1997
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Dyes; Photochromism; Phase transformations; Crystallization; Size effect; Amorphous state; Absorption spectra; Experimental study; Organic compounds
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.36.3736

Optical properties of photochromic dyes, 1,2-bis(2-methylbenzo[b]thiophen-3-yl)perfluorocyclopentene (BFCP) and cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene have been studied in the solid state. These photochromic dyes have been found to form a stable amorphous solid state when they are sandwiched between two glass plates. The time for the transition from the amorphous state to the crystalline state increases with decreasing distance between the two glass plates. The amorphous solid films clearly show photochromism upon light irradiation and also a marked change in photoluminescence intensity. The crystallization of the open-ring BFCP isomer is much faster than that of the closed-ring isomer. It has also been revealed that the photoluminescence spectrum of BFCP changes upon photoisomerization.