Electrical properties and dielectric relaxation of thermally evaporated zinc phthalocyanine thin films

Zeyada, H.M.; El-Nahass, M.M.

doi:10.1016/j.apsusc.2007.07.175

Cited by 62 publications

(29 citation statements)

References 32 publications

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“…20,21,22,23 (Figures 1c and d). 24 The FT-IR spectroscopy results further confirm the genuineness of the a-form of ZnPc NW as it displays a fingerprint-bending mode of C-H at 724 cm À1 together with the vibrational mode of the center cyclic ring at 773 cm À1 (Supplementary Figure S2). 25,26 Note that ZnPc NW samples are collected from multiple reaction batches for the PW XRD measurements.…”

Section: Resultssupporting

confidence: 57%

Significant increase in the water dispersibility of zinc phthalocyanine nanowires and applications in cancer phototherapy

et al. 2012

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The phototherapy is one of the widely accepted noninvasive clinical methodologies to eradicate cancer cells owing to its minimal side effects and high selectivity to the light of specific wavelength. As represented by photodynamic (PD) and photothermal (PT) therapy, the phototherapy requires light and photosensitizer to generate reactive oxygen species and heat, respectively. Zinc phthalocyanine (ZnPc) is one of the promising photosensitizers as it has a strong absorption cross-section in the spectral range of 650-900 nm that guarantees maximum tissue penetration. One critical issue in using Pc molecule, including ZnPc as a biocompatible sensitizer is the poor water solubility. To increase water solubility, various chemical modifications inducing hydrophilicity have been widely attempted to introduce various functional groups in the ZnPc backbone. We report that ZnPc nanowires (NWs) directly grown from ZnPc powder by vaporization-condensation-recrystallization process show surprisingly increased water dispersibility without any functionalization. The ZnPc NW solution exhibits highly efficient dual PD and PT effects upon the irradiation of near infrared (808 nm) laser. The dual phototherapeutic effect of ZnPc NW is proven to enhance cytotoxic efficiency according to both in vitro and in vivo experimental results. NPG Asia Materials (2012) 4, e12; doi:10.1038/am.2012.22; published online 13 April 2012Keywords: nanowire; photosensitizer; phototherapy; Zinc phthalocyanine INTRODUCTION Phototherapy, represented by photodynamic therapy (PDT) and photothermal therapy (PTT), is an advanced modality for the treatment of malignant tumors as it is widely used for clinical cancer treatments. PDT selectively destroys neoplastic lesions using cytotoxic reactive oxygen species (ROS) generated by light activation of the photosensitizer. 1,2 One of the crucial factors determining the PDT efficacy is the photochemical and photophysical properties of the photosensitizer. 3,4 Currently, four main classes of photosensitizer, such as porphyrin derivatives, chlorins, porphycenes, and phthalocyanines (Pcs), have been approved by the U.S. Food and Drug Administration (FDA) for clinical applications against cancer. 5,6 Among these, metallo-phthalocyanine has attracted considerable interest, having a photodynamic (PD) property that can be readily tuned by the type of central metal ion and the functional groups introduced as a Pc ring substituent. Zinc phthalocyanine (ZnPc) is known to exhibit a high PD effect as it possesses a diamagnetic Zn(II) central metal ion whose d shell is fully occupied, by which the yield of triplet excited state with long lifetime essential for the generation of ROS becomes high. 7 Moreover, ZnPc has

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Section: Resultssupporting

confidence: 57%

Significant increase in the water dispersibility of zinc phthalocyanine nanowires and applications in cancer phototherapy

et al. 2012

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“…The real dielectrical constant, e r , can be calculated from the measured capacitance in parallel mode by the following equation [49][50][51]:…”

Section: Dielectrical Properties Of Panaa and Panaa-ni Compsoitesmentioning

confidence: 99%

Effect of Doping with Nickel Ions on the Electrical Properties of Poly(aniline-co-o-anthranilic acid) and Doped Copolymer as Precursor of NiO Nanoparticles

Zoromba

El-Ghamaz

Alghool

2015

J Inorg Organomet Polym

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Poly(aniline-co-o-anthranilic acid) (PANAA) and its nickel composite (PANAA-Ni) are successfully prepared based on oxidative chemical polymerization via two comparative in situ and ex situ polymerization methods. PANAA copolymer contains aniline, and o-anthranilic acid moieties, were doped with different concentrations of nickel ions. The ratios of aniline, o-anthranilic acid, and nickel chloride were (1:1:0.5) and (1:1:1), respectively. The effect of nickel moiety on the properties of polyconjugated polymers, and their spectral characteristics (UVVis absorption spectra, FTIR, thermal stability) were recorded. TGA analysis confirmed that the poly(aniline-coo-anthranilic acid)/nickel (PANAA-Ni) composites, which were prepared by in situ or ex situ polymerization method, are more thermally stable than the pure PANAA copolymer. The XRD revealed that the pure and PANAA-Ni (prepared by ex situ polymerization method) is completely amorphous structure, while the PANAA-Ni composite (prepared by in situ polymerization method) is a mixture of crystalline and amorphous phases. The temperature dependence of dielectric constants (e r and e i ) as well as AC conductivity (r ac ) were investigated in the temperature range of 300-383 K and test frequency range of 0.1-100 kHz. All the tested samples showed semiconductor behavior. The values of thermal activation energies DE1 and DE2 for PANAA copolymer are calculated, and found to be in the range of 0.03-0.1 eV and 0.58-1.88 eV, respectively. We calculated DE1 and DE2 for PANAA-Ni composite, and we found their values in the range of 0.14-0.27 eV and 0.41-0.58 eV, respectively. Moreover, Nanocrystalline nickel oxide NiO powder was prepared by thermal decomposition route of (PANAA-Ni) composites, which was prepared by in situ polymerization method. The size of the obtained nickel oxide nanoparticle was determined by transmission electron microscope .

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“…1, 2 Among the metal organic molecules, the metal-phthalocyanine (MPc) molecules have gained large attention because of their high thermal and chemical stability, high intrinsic charge carrier mobility, the ambipolarity of the charge carrier transport, and high absorption coefficient of order of 10 5 cm −1 . 3 Hence they have been applied to wide varieties of fields such as optolelectronics and electronics devices, [4][5][6][7] namely organic light emitting diodes (OLEDS), 8 photovoltaic devices, 9 memory devices, 10 organic solar cells 11,12 and sensors. 13 Therefore it is necessary to have proper understanding of surface morphology and growth mechanism of MPc's compounds in thin films for their technical application.…”

Section: Introductionmentioning

confidence: 99%

Effect of annealing on the growth dynamics of ZnPc LB thin film and its surface morphology

2014

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The ZnPc molecules in the thin film prepared by Langmuir-Blodgett (LB) process in asdeposited state has been found to have an edge on orientation with average tilt angle of 64.3 ° as confirmed from the Pressure-Area (π-A) isotherm and X-ray diffraction (XRD) study. The ZnPc LB thin film has been observed to have abnormal growth mode at higher annealing temperature and it is mainly driven by minimization of surface free energy which lead to large increase in crystallinity of the film. Kinetically favored orientational and structural transitions of ZnPc thin film during annealing and their effect on the surface morphology of the thin film has been studied using scaling concepts. The scaling exponents 1) root mean square (RMS) roughness σ, 2) roughness exponent α and, 3) in plane correlation length ξ are calculated from the HDCF g(r) and ACF C(r). The RMS surface roughness σ is found to be dependent on the as defined short wavelength undulations (ρ) and long wavelength undulations (χ). Both ρ and χ are the function of all the three scaling exponents. σ has been observed to be maximum for the ZnPc thin film annealed at 290 °C, since the χ shoot to maximum value at this temperature due to the formation of small domains of ZnPc nanorods. The self affinity of the ZnPc thin film is found to decrease on annealing as obtained from both power spectral density (PSD) and HDCF g(R) & ACF C(R) study, which confirms that the dimension of surface morphology of the ZnPc LB thin film transform towards 2D with increase in annealing temperature.

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Electrical properties and dielectric relaxation of thermally evaporated zinc phthalocyanine thin films

Cited by 62 publications

References 32 publications

Significant increase in the water dispersibility of zinc phthalocyanine nanowires and applications in cancer phototherapy

Significant increase in the water dispersibility of zinc phthalocyanine nanowires and applications in cancer phototherapy

Effect of Doping with Nickel Ions on the Electrical Properties of Poly(aniline-co-o-anthranilic acid) and Doped Copolymer as Precursor of NiO Nanoparticles

Effect of annealing on the growth dynamics of ZnPc LB thin film and its surface morphology

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