Triphenylamine photoconductive polymers for high performance photorefractive devices

• Two kinds of composite based on acrylate triphenylamine polymers are compared.
• Good photorefractive performance can be achieved at a moderate electric field.
• A modification by methoxy group at para-position increases HOMO level.
• Methoxy group significantly improves chromophore orientation.
• The triphenylamine plasticizer can act as an effective trap.

Photorefractive performances of the composites using two kinds of photoconductive triphenylamine-based polymer have been compared and investigated. One polymer is poly(4-(diphenylamino)benzyl acrylate) (PDAA). The other is newly synthesized one of photoconductive acrylate polymer with methoxy substituted triphenylamine pendant, poly(4-((4-methoxyphenyl)(phenyl)amino)benzyl acrylate) (PMPAA). The methoxy substituent in PMPAA does not only shift the highest occupied molecular orbital (HOMO) level of the polymer, but also effectively enhances the chromophore orientation. Larger phase shift is confirmed by using the modified photoconductive polymer of PMPAA. The plasticizer of (4-(diphenylamino)phenyl)methanol (TPAOH) (IP = −5.64 eV) works as an effective trap in the PDAA (IP = −5.69 eV)-based composite, resulting in higher diffraction efficiency. Diffraction efficiency of 70% and fast response time of 25 ms (dominant) is measured at 532 nm under the moderate electric field of 45 V/μm.

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