Sho Tsujimura

High-Speed Photorefractive Response Capability in Triphenylamine Polymer-Based Composites

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.

Dynamic holographic images using photorefractive composites

We have studied the effect of Mw of PVCz on dynamic holographic imaging. The appropriate performance for dynamic holographic imaging was obtained by the photorefractive polymeric composite film with Mw:23,000 PVCz.

Electron dominated grating in a triphenylamine-based photorefractive composite

Photorefractive (PR) composites based on a p-type triphenylamine photoconductor with the nonlinear optical chromophore 7DCST have been fabricated without using a typical sensitizer of C60 or its derivative PCBM. The effect of an added electron trap, Alq3, on the PR performance has been investigated through optical wave mixing experiments with a pumping wavelength of 532 nm. The decay time of the photo-induced refractive index grating in the dark was significantly improved by the addition of Alq3. The net gain measured by two-beam coupling experiments was also improved and was 80 cm−1 for the composite with Alq3 but 60 cm−1 for that without. By observing the direction of the energy transfer in the two-beam coupling signals for the composite without Alq3, the sign of the grating formed by mobile electrons was confirmed in addition to the grating formed by the mobile holes. Moreover, the PR performance was proven to be dependent on the history of the recording. It is concluded that the PR performance in the composite without Alq3 was suppressed by the grating formed by mobile electrons. The optical gain obtained by the sole electron-dominated grating was evaluated to be at least −46 cm−1.

Enhanced photoconductivity by melt quenching method for amorphous organic photorefractive materials

For many optical semiconductor fields of study, the high photoconductivity of amorphous organic semiconductors has strongly been desired, because they make the manufacture of high-performance devices easy when controlling charge carrier transport and trapping is otherwise difficult. This study focuses on the correlation between photoconductivity and bulk state in amorphous organic photorefractive materials to probe the nature of the performance of photoconductivity and to enhance the response time and diffraction efficiency of photorefractivity. The general cooling processes of the quenching method achieved enhanced photoconductivity and a decreased filling rate for shallow traps. Therefore, sample processing, which was quenching in the present case, for photorefractive composites significantly relates to enhanced photorefractivity.

Triphenylamine-Based Photorefractive Devices for Real-Time Holographic Applications

We present here updatable holographic imaging using low electric field driven triphenylamine-based photorefractive polymeric composite device.

Photorefractivity of triphenylamine polymers

We present here the enhanced photorefractive performance and dynamic holographic image of poly(4-diphenylamino)styrene (PDAS)-based photorefractive polymeric composites (PPCs). PDAS and FDCST were synthesized as a photoconductive polymer and a nonlinear optical (NLO) dye, respectively. PPC films including PDAS, TPA (or ECZ), FDCST, and PCBM were investigated. The photorefractive quantities of the PDAS-based PPCs were measured by a degenerate four-wave mixing (DFWM) technique. Additionally, the dynamic holographic images were recorded through an appropriate PDAS-based PPC. Those dynamic holographic images clearly duplicate the original motion with high-speed quality. The present approach provides a promising candidate for the future application of dynamic holographic displays.