Photoconductivity in crystalline phthalocyanines

Xavier, Francis; Goldsmith, George J.

doi:10.1007/bf02749665

Cited by 7 publications

(12 citation statements)

References 2 publications

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“…The conductivities of solid complexes made up of polycyclic aromatic hydrocarbons and halogens have been reported in the range 1-10-3 fl-1 cm-1 (Wright 1989). For example, halogen complexes of Pcs are still topic of strong interest in application oriented research (Inabe et al 1985;Xavier and Goldsmith 1995). Electrons associated with conjugate bonds of organic compounds are not localized on a particular atom but are located over the entire molecule.…”

Section: Inorganicmentioning

confidence: 99%

“…Assuming that the 'three-pointmethod' can be applied to organic thin films the band gaps can be calculated. It has been shown that the organic materials, such as phthalocyanines, have multiband system (Xavier and Goldsmith 1995).…”

Section: Interpretation Of the Er Spectramentioning

confidence: 99%

“…The most common polymorphic forms of Pcs are designated s-form and //-form (Moser and Thomas 1963;Gutmann and Lyons 1981;Simon and Andr6 1985). The s-form occurs as polycrystalline films when sublimed under vacuum onto cool (room temperature) substrates, while the//-form is crystallized into single crystals by vacuum sublimation at a temperature around 460°C (Xavier and Goldsmith 1995). The a-form is tetragonal having six molecules per unit cell but the//-form is monoclinic having only two molecules per unit cell (Robertson 1935(Robertson , 1936Moser and Thomas 1963;Aoyagi et a11971;Schoch et a11988).…”

Section: Introductionmentioning

confidence: 99%

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Application of electroreflectance analysis for organic semiconductor thin films

Xavier¹

1997

Bull Mater Sci

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Many organic semiconductors with conjugate bond structure possess photoconductivity. Conduction mechanism of organic materials exhibits 'dualism' since both intramolecular as well as inter-molecular aspects are involved in the excitation, absorption and transport of charge carriers. Modulation spectroscopy promises to be the most accurate method for analysis of organic photoconductors, especially of thin films. In this technique a periodic perturbation is applied to the material under study and the effect of the perturbation is separated from reflection or absorption while scanning through a given wavelength range by use of lock-in phase sensitive detection method. In electromodulation, particularly in electrolyte electromodulation, the applied field on the material produces changes in the dielectric function which corresponds to the change in reflectance. When the applied field is low the line-shape of spectrum is third-derivative like in comparison with the unmodulated reflectance spectrum. Using Aspnes three-point method the transitions corresponding to critical points can be determined. When the field is intermediate Franz-Keldysh oscillations, which are dc bias dependent, appear on the higher energy side of the transition energy from which the role of intra-molecular as well as intermolecular aspects in conduction mechanism can be understood and the carrier concentration could be determined. Though the electroreflectance method has been developed for inorganic semiconductors, it could be effectively applied for organic/molecular semiconductors as well if the constituent molecules are assumed to be the lattices. The study of organic photoconductors is very important since they are more and more promising especially in photocopying, photovoltaic and solar cells.

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Section: Inorganicmentioning

confidence: 99%

Section: Interpretation Of the Er Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of electroreflectance analysis for organic semiconductor thin films

Xavier¹

1997

Bull Mater Sci

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“…The most common representatives of organic metal complexes include metal phthalocyanines . This series of compounds along with high catalytic activity displays good semiconductor properties, high thermal and chemical stability, which contribute to their wide application: from paints to catalysts …”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12] The most common representatives of organic metal complexes include metal phthalocyanines. [13,14] This series of compounds along with high catalytic activity displays good semiconductor properties, high thermal and chemical stability, [15] which contribute to their wide application: from paints [16] to catalysts. [17] Due to their ability to display different oxidation degree, transition metals can interact with the polymer chain.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cobalt Phthalocyanine on Synthesis and Physicochemical Properties of Polyaniline

2019

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Organic transition metal complexes are successfully used in polymerization due to their catalytic activity in oxidative reactions. Here, polyaniline was synthesized with cobalt phthalocyanine as catalysts for the aniline oxidative polymerization. The conditions for obtaining polyaniline significantly affect the final product and the introduction of the component into the reaction mixture leads to a change in the physicochemical properties of the polymer. Thus, the effect of the catalyst on the polymer chain was determined using FTIR, UV‐visible spectral methods and atomic adsorption analysis. Electrical conductivity, thermal stability, electrochemical parameters (HOMO‐LUMO, band gap), surface morphology, and fluorescence emission spectra were estimated for the polymer samples obtained. The study of synthesized polymeric materials resulted that the use of cobalt phthalocyanines in the aniline oxidative polymerization process leads to better physicochemical properties, namely electrical conductivity, band gap and fluorescence quantum yield.

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Role of Metal Phthalocyanine in Redox Complex Conductivity of Polyaniline and Aniline Black

Xavier¹,

Inigo²,

Goldsmith

1999

J. Porphyrins Phthalocyanines

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Polyaniline (PA) and aniline black (AB) were prepared in powder form by the chemical method of oxidative polymerization, from which free-standing thin films were obtained by solvent evaporation using N-methyl pyrrolidinone ( NMP ). The thin films contained 2, 4, 6 or 8 wt% AB. Electrical measurements showed that the samples containing 4% AB exhibited the highest photoconductivity of the four concentrations. Thus there appears to be a critical ratio of PA to AB for maximum photoconductivity. Annealing up to 570 K has little effect on the conductivity. Upon adding a small quantity of copper phthalocyanine ( CuPc ) to the PA + AB, the electrical conductivity increased considerably and the optical absorption was extended from the UV to the near IR. The electrical conductivity mechanism is a consequence of a redox process, since AB is the oxidized state of PA and, upon illumination, there is an exchange of charge carriers. The extension of the range of optical absorption upon addition of CuPc is interpreted to suggest that CuPc photosensitizes the material and enhances the carrier transport process in the redox couple. The activation energy from the temperature-dependent conductivity and the band gap from the electrolyte electroreflectance method were determined. The activation energy for 0.4% CuPc is lowest (0.52 eV) and the corresponding band gap is determined to be 3.0 eV. This organic compound could be a good candidate for inexpensive, reliable and efficient solar energy-converting devices.

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Photoconductivity in crystalline phthalocyanines

Cited by 7 publications

References 2 publications

Application of electroreflectance analysis for organic semiconductor thin films

Application of electroreflectance analysis for organic semiconductor thin films

Effect of Cobalt Phthalocyanine on Synthesis and Physicochemical Properties of Polyaniline

Role of Metal Phthalocyanine in Redox Complex Conductivity of Polyaniline and Aniline Black

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