A new type of light stabilizer for dye layers of optical disks: Tetracyanoquinodimethane derivatives

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.