Photorefractive dynamics in poly(triarylamine)-based polymer composite: an approach utilizing a second electron trap to reduce the photoconductivity

Abstract

The effects of a second electron trap, tris-(8-hydroxyquinoline)aluminum (Alq3), 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7), or bathophenanthroline (BPhen), on the photorefractive (PR) sensitivity, response time, and diffraction efficiency are investigated for a methyl-substituted poly(triarylamine) (PTAA)-based PR composite. An extremely high PR sensitivity of 1145 cm2 J−1 with a sub-millisecond response time of 397 μs with an internal diffraction efficiency of 73.3% is achieved at an electric field of 60 V μm−1 for the PTAA-based PR composite containing BPhen. The fast, sub-millisecond response time and fourth-order sensitivity are mainly contributed to the reduction of the photocurrent due to the formation of a charge-transfer complex between PTAA and BPhen. Furthermore, the obtained results estimate the response time to be 97 μs for the PTAA-based PR composite containing an appropriate second electron trap with a photoconductivity of 3.3 nS cm−1.