Improvement on the photorefractive performance of a monolithic molecular material by introducing electron traps

The electron-injecting material, tris(8-hydroxyquinoline) aluminum (Alq3), was introduced into photorefractive (PR) samples containing the (9-ethyl-9H-carbazol-3-ylmethylent)-(4-nitrophenyl)-amine (ECYENPA) molecule, which has been proved to possess the fine functions of both electro-optic effect and hole transportation. A small amount of Alq3 forms quantum dots in ECYENPA, serving as electron traps and leading to a great enhancement of the PR effect. A large two-beam coupling coefficient of 424cm−1 (at 44.6V∕μm) was observed in a sample doped with 2wt% of Alq3, in contrast to a value of 232cm−1 for a sample without Alq3. Moreover, the measured response time was one order of magnitude shorter than that of the undoped sample.