S. Morishima et al., A new type of light stabilizer for dye layers of optical disks: Tetracyanoquinodimethane derivatives, JPN J A P 1, 38(3B), 1999, pp. 1634-1637
A new technology to improve the light fastness of cyanine dye layers of a c
ompact disk recordable (CD-R) or a digital video disk recordable (DVD-R) wi
thout using any singlet oxygen quenchers was discussed. The light fastness
of dicarbocyanine dye layers of a CD-R was improved by doping with tetracya
noquinodimethane (TCNQ) derivatives of various reduction potentials (E-1/2(
RED)). The optimum potential was found to be around 0 V vs saturated calome
l electrode (SCE). Doping with TCNQ derivatives was found to be effective a
lso for the improvement of light fastness of the carbocyanine dye layers wh
ich have optical properties suitable for a. DVD-R disk. Excessive electron
demanding TCNQ derivatives (E-1/2(RED) > 0), however, showed rather poor ji
tter and block-error rate (BLER) after exposure to a xenon lamp as compared
to a TCNQ derivative (TCNQ1) with an optimal reduction potential (ca. 0 V
vs SCE). Since TCNQ derivatives have no absorption band in a red to near in
frared region, the CD-R or the DVD-R having cyanine dye layers doped with T
CNQ derivatives exhibit higher reflectivity than those with such singlet ox
ygen quenchers as diimmonium salts.