CRYSTAL-GROWTH AND CHARACTERIZATION OF A 1ST (SPACE-CHARGE INDUCED) PHOTOREFRACTIVE ORGANIC-CRYSTAL

Dissolving congruent-to 1000 ppm (1 ppm = 1-mu-mol/mol) 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a superheated melt of 2-cyclooctylamino-5-nitropyridine (COANP) leads to formation of mainly [TCNQ]2(-2) that is incorporated into the COANP crystal lattice by supercooled melt growth at supercoolings smaller than DELTA-T less-than-or-equal-to 0.5 - 1.5-degrees-C. Obtained doped COANP crystals show an extra optical absorption at lambda-max congruent-to 650 nm and are photorefractive. The found photorefractive effects are most probably induced by the presence of approximately 50 ppm [TCNQ]2(-2).