Dichromated Poly Vinyl Alcohol Research Articles

Environmental conditions influence for real-time hologram formation on dichromated polyvinyl alcohol NiCl2·6H2O doped films

The real-time holographic gratings recording are studied by the presence of a metallic salt. The experimental process refers to analysis of diffraction efficiency by the influence of humidity in the coating solution on holograms formation in presence of electrical potential. The diffraction efficiency is measured as a function of the exposure energy until reach the saturation. The influence of the hologram parameters to get the diffraction efficiency is studied at room conditions.

Solvent Effect of the Passivation Layer on Performance of an Organic Thin-Film Transistor

We studied the passivation of pentacene organic thin-film transistors (OTFTs) on plastic using four kinds of organic layers: photopatternable acryl (PA), polyvinylalcohol (PVA)/dichromated polyvinylalcohol (D-PVA), PVA/D-PVA/PA, and parylene-C. The initial mobility of the OTFTs was ∼ 1.0 cm 2 /V s and the on/off current ratio was ∼10 7 . The drop in the on-current and the increase in the off-currents were significant when PA was used as a passivation layer because of the damage to the pentacene active layer by the organic solvent in PA solution. On the other hand, there was little change in the performance of the OTFT when PVA/D-PVA was used as the passivation layers on the pentacene. This was done to reduce the concentration of metal ionic impurity at the interface of the pentacene and PVA. The OTFT with the passivation layers exhibited a field-effect mobility of 0.8 cm 2 /V s and on/off current ratio of 10 7 . This means that the water soluble PVA can minimize the damage to the pentacene and prevent the penetration of the organic solvent in PA solution.

Dichromated polyvinylalcohol: key role of chromium(V) in the properties of the photosensitive material

The photochemical behavior of dichromated polyvinylalcohol (DCPVA) films was investigated to elucidate the first step of the reaction taking place in the photosensitive material. The work was completed for comparison by the investigation of DCPVA solutions.The difference in behavior appears in the ground state and in excited state. Processing a film modifies not only the spectral features of chromium(VI) but also the photochemical behavior. The photoredox process does not occur in basic aqueous DCPVA solution (pH=9) whereas it takes places in films prepared from that solution. The one electron photoreduction of Cr(VI) into Cr(V) is very efficient in both DCPVA films (acidic or basic) with Φ=0.65±0.05. The Φ values were calculated from the Cr(V) formation stable enough under the experimental conditions. All the results are in favor of the involvement of a complex between Cr(VI) and OH groups of polyvinylalcohol (PVA). ESR spectroscopy measurements upon irradiation further confirmed the formation and the stability of Cr(V) in PVA matrix. A very nice correlation appeared between Cr(V) behavior and the diffraction efficiency of holograms recorded in DCPVA as reported in the literature.

Dichromated polyvinyl alcohol as a real-time hologram recording material: some observations and discussions

The real-time hologram formation in dichromated polyvinyl alcohol films has been studied in the presence of external electron donors included in the formulation. The effect of different external electron donors on the photosensitivity and real-time diffraction efficiency of volume holographic transmission gratings has been reported. The electron donors studied were found to be detrimental to both holographic characteristics, even in small concentrations. Some parameters that influence the holographic performance are discussed, and results are given. The photochemical recording mechanism in dichromated polyvinyl alcohol in the presence and absence of electron donors is briefly discussed.

Dichromated polyvinyl alcohol for real-time hologram recording: Effect of humidity

The effect of environmental humidity on the photosensitivity and real-time diffraction efficiency has been studied in dichromated polyvinyl alcohol (DC-PVA) films with and without external electron donors. High relative humidity has been found to significantly improve the photospeed and the real-time diffraction efficiency for almost all of the studied formulations. The results and possible photochemical reactions in the recording mechanism are briefly discussed.

Dichromated polyvinyl alcohol films used as a novel polarization real time holographic recording material

Real time recording and reading of volume transmission holograms were performed with dichromated polyvinyl alcohol thin solid films (31 microm) that were easy to prepare and use. Real time holograms of high diffraction efficiency were produced without any chemical development, but these films were not erasable. The present holographic study of dichromated polyvinyl alcohol films permits the consideration of many engineering applications.