We present here the poly(4-diphenylamino)styrene (PDAS)-based photorefractive composites with a high-speed response time. PDAS was synthesized as a photoconductive polymer and photorefractive polymeric composite (PPC) films by using triphenylamine (TPA) (or ethylcarbazole, ECZ), 4-homopiperidino-2-fluorobenzylidene malononitrile (FDCST), and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were investigated. The photorefractive quantities of the PDAS-based PPCs were determined by a degenerate four-wave mixing (DFWM) technique. Additionally, the holographic images were recorded through an appropriate PDAS-based PPC. Those holographic images clearly reconstruct the original motion with high-speed quality. The present approach provides a promising candidate for the future application of dynamic holographic displays.

In organic optical semiconductors, it is rather challenging to achieve precise control of photoconductivity and charge trapping, which determines the device performance. This paper reports on enhanced photorefractive response rate through control of the photoconductivity and trapping rate in organic triphenylamine-based photorefractive materials by means of bulk state tuning. The bulk state in organic triphenylamine-based photorefractive composites was controlled through a rapid cooling process from various melting temperatures during sample fabrication. The photoconductivity and trapping rate were determined from photocurrent measurements. Fabrication at lower melting temperatures enhanced the trapping rate for deep traps, whereas it reduced the trapping rate for shallow traps. As a result, a faster photorefractive response was obtained.

To expand upon our previous report [Appl. Phys. Express 5, 064101 (2012) 064101], we provide here the modified poly(4-diphenylaminostyrene) (PDAS)-based photorefractive (PR) device on the basis of wavelength dependency, and demonstrate dynamic holographic images by using the PDAS-based PR device under the obtained appropriate conditions. The PR devices containing the triphenylamine unit have potential application to dynamic holographic images, which will be useful for real-time holographic displays.

No abstract

A video rate operation (30 Hz) with more than 80% diffraction efficiency and net gain of 89 cm −1 was reported in a photorefractive (PR) composite based on poly((4-diphenylamino)benzyl acrylate) (PDAA). A diffraction efficiency of 60% was attained at 60 Hz. To reveal the mechanism behind such highperformance, transient photocurrent measurements were performed. The investigation clearly showed the importance of the (4-(diphenylamino)phenyl)methanol (TPAOH) plasticizer in the charge transport process of the PR composite. The function of TPAOH was demonstrated as a normal plasticizer, as well as an effective photoconductivity enhancement factor of the composite. The analysis of the shapes of the transient photocurrent curve with two trapping sites revealed that TPAOH strongly assisted charge transport in PDAA. The response time of the PR composite was improved by increasing the TPAOH concentration and suppressing the shallow trapping effect. In contrast, the reference 2,4,6-trimethyl-N,N-diphenylaniline (TAA) plasticizer was found to significantly suppress the photocurrent (up to 100 times) compared to that of the TPAOH samples. The replacement of TPAOH by TAA degraded the response time of the diffraction beam. This was attributed to the low-scattering effect caused by the TAA. The study revealed that the deep and shallow traps originate from the PDAA polymer.