Nickel Phthalocyanine Thin Films Research Articles

Magneto-electrical properties of nickel phthalocyanine thin film and its application in organic solar cells

The nickel phthalocyanine (NiPc) thin film has been explored for magneto-conductance and optoelectrical properties. The surface morphology and the opto-electrical properties of thin films of NiPc have been observed as a good candidate for the applications in polymer solar cells. The AFM images show an almost continuous surface over the studied area. The spin interaction, the disordering of the spins part, and their suitable models have been discussed by the magneto-conductance properties of the thin films. The relaxation time of carriers and traps filling phenomena with applied bias are discussed by the impedance spectroscopy. The thin films of NiPc have been introduced as a hole interface buffer layer in the standard structure of P3HT: PCBM solar cells. The power conversion efficiency (PCE) of the optimized solar cell with NiPc is ∼3.17% and the fill factor (FF) is ∼69%., these device parameters are higher (PCE increased by ∼65% and FF by ∼39%) as compared to the organic solar cells fabricated without NiPc thin films in the same batch. The improved performance of organic solar cells attributed due to lowering the series and shunt resistance.

Investigate the Structural and Optical Properties of Nickel Phthalocyanine (NiPc)Thin Films Prepared by Chemical Spray Pyrolysis Method.

The technique of the chemical spray pyrolysis has been employed to deposit Nickel Phthalocyanine (NiPc) on different substrate types at temperatures 150 °C to investigate their structural, Scanning Electron Micrographs, X-ray diffractograms and optical properties. The results of X-ray diffraction show that structure of the powder is polycrystalline with monoclinic structure, and the results of XRD for a thin film of NiPc shows polycrystalline with a fairly weak degree of crystallization, SEM revealed that the surface of the film is usually homogeneous, the roughness of NiPc films was evaluated by AFM technique and the results showed that the grain size increases with increasing of concentration. The optical measurement using UV-Visible Spectra showed that the NiPc thin films have an optical constant like the absorption coefficient and have a direct energy gap for all samples.

Electrochemical properties of nickel phthalocyanine: The effect of thin film morphology tuned by deposition techniques

The electrical and optical properties of thin films can be modulated by its supramolecular arrangement being this latter closely related to the fabrication method. Here, we are exploiting the impact of deposition techniques of nickel phthalocyanine (NiPc) and tetrasulfonated nickel phthalocyanine (NiTsPc) thin films on their supramolecular arrangement. Deposition techniques as Langmuir-Schaffer (LS), Langmuir-Blodgett (LB), physical vapor deposition (PVD), dipping- and spray-Layer-by-Layer (LbL) were applied for fabrication of the thin films. Linear growth was observed for all films indicating control of the amount of NiPc or NiTsPc deposited in each technique at nm scale. Fourier-transform infrared absorption spectroscopy (FTIR) and micro-Raman scattering confirmed the chemical stability of NiPc and NiTsPc concerning the deposition technique (water or heat). Besides, FTIR and X-ray diffraction data suggested that all thin films present isotropy in terms of molecular organization, with a predominance of the crystalline α-phase in the case of PVD, LB, and LS films. Atomic force microscopy images revealed irregularities at the surface for all thin film with the roughness/thickness ratio being 4.5% for PVD, 9% for both LB and LS films, and 18 and 35% for spray- and dipping-LbL films, respectively. The electrochemical behavior in both inert electrolyte and dopamine (DA) solution was directly dependent on the film morphology (molecular aggregates and surface roughness). The increase of the roughness in relation to thickness promoted films better electrochemical responses to DA oxidation. The dipping-LbL films showed the smaller potential of DA oxidation (0.114 V), even compared to the bare substrate (0.133 V). The deposition technique showed to be an suitable tool to tune the supramolecular arrangement of phthalocyanine forming thin films, which improve and/or change the electrochemical properties of the device.

Impact Thickness on Structural and Electrical Characterization of Nickel Phthalocyanine Thin Films

Thin films of Nickel Phthalocyanine have been prepared by evaporation technique for (50 - 350 nm) of thickness. XRD studies show that the thin films have single crystalline structure for low thicknesses with (100) orientation and the crystallite size increased with increased thickness. Also from the AFM technique for NiPc films, the roughness was determined and the grain size increases with increasing of thickness from except at thickness 350 nm. The studies of electrical properties, morphology and orientations of the crystallites are important to understand and predict the nature of the films and essential for their successful applications in solar cell and sensors. The electrical properties of these films were studied with different thickness, NiPc has three activation energy. Carrier’s concentration and mobility was calculated. Hall measurements showed that all the films are p-type.

Investigation of Nickel Phthalocyanine Thin Films for Solar Cell Applications

Investigation of Nickel Phthalocyanine Thin Films for Solar Cell Applications

Investigation of Nickel Phthalocyanine Thin Films for Solar Cell Applications

Ni-Phthalocyanine thin films were thermally evaporated with different substrate temperatures (300 - 450) K on (silicon wafer, glass) substrates. The chemical bonds of NiPc powder were investigated by FTIR spectrum, which introduce good information for NiPc bonds and their locations. The optical properties have been studied by UV-Visible, and Photoluminescence (PL) Spectra. The NiPc thin films have direct gap for all samples. The values of energy gap which is calculated by PL spectra are lower than those calculated by Tauc equation. It is found there are three activation energies, the mobility and concentration of carriers have been measured and, the NiPc films are p-type. P-NiPc/n-Si HJ solar cell was fabricated at substrates temperatures (300, 400) K. From I-V and C-V characteristic, abrupt junction has been found, photovoltaic characteristics have been observed with Voc of (0.335 - 0.415) V, and Isc of (2.77 - 4.26) μA, and the efficiency of (3.08 - 5.03)% at room temperature and substrate temperature (300, 400 K) and under illumination of 55 mW/cm2 using Halogen lamp. Ideality factors of the junction increase from (0.61 - 0.73) and barrier height increases from 2.53 eV to 3.69 eV while shunt resistance decreases from 3.76 KΩ to 2.59 KΩ and series resistance decreases slightly from 0.24 KΩ to 0.23 KΩ. The fill factor decreases from 0.46 to 0.4 with the increase of substrate temperature.

Silver Nanoparticle Effect on Spectral-Kinetic Properties of Thin Nickel Phthalocyanine Films

We have investigated spectral and spectral-kinetic properties of hybrid plasmonic nanocomposites on silver nanoparticle monolayers and thin nickel phthalocyanine films. The spectroscopic results obtained by the femtosecond pump-probe technique demonstrate that a fast optical response in the range of long-wavelength nickel phthalocyanine electronic absorption bands becomes observable and registered when the nickel phthalocyanine thin films contact with silver nanoparticles. This could be assigned to the plasmon-related modification and the enhancement of organic subsistent absorption at steady-state absorption spectra of hybrid nanostructures.

Comparison of interaction mechanisms of copper phthalocyanine and nickel phthalocyanine thin films with chemical vapours

The present study deals with comparing interaction mechanisms of copper phthalocyanine and nickel phthalocyanine with versatile chemical vapours: reducing, stable aromatic and oxidizing vapours namely; diethylamine, benzene and bromine. The variation in electrical current of phthalocyanines with exposure of chemical vapours is used as the detection parameter for studying interaction behaviour. Nickel phthalocyanine is found to exhibit anomalous behaviour after exposure of reducing vapour diethylamine due to alteration in its spectroscopic transitions and magnetic states. The observed sensitivities of copper phthalocyanine and nickel phthalcyanine films are different in spite of their similar bond numbers, indicating significant role of central metal atom in interaction mechanism. The variations in electronic transition levels after vapours exposure, studied using UV–Visible spectroscopy confirmed our electrical sensing results. Bromine exposure leads to significant changes in vibrational bands of metal phthalocyanines as compared to other vapours.

Study on Optical and Electrical Properties of Bismuth-Doped Nickel-Phthalocyanine Thin Films

The objective of this work is to investigate the optical and electrical properties of bismuth-doped nickel-phthalocyanine thin films (Bi-doped NiPc). The doped films were prepared by thermal co-evaporation as a function of Bi concentration. The amount of Bi in NiPc was controlled via different deposition rates between metal dopant and organic host. The optical properties of the hybrid films were characterized by spectroscopic techniques. Furthermore, the electrical properties e.g. charge carrier concentration and carrier mobility of Al/Bi-doped-NiPc/ITO devices were characterized by current-voltage and capacitance-voltage measurements. The results of optical properties suggest that the crystalline packing of NiPc molecules in all preparation conditions is a combination of α-phase (majority) and β-phase (minority). However, the evolution of β-phase NiPc is observed with the increase of metal doping concentration. Raman spectroscopic results reveal that there is no chemical bond taken place between Bi and NiPc. In addition, with increasing dopant concentration, electrical properties present the enhancement of conducting current of hybrid devices as result from the increment of both charge carrier concentration and charge carrier mobility.

Growth and characterizations of tin-doped nickel-phthalocyanine thin film prepared by thermal co-evaporation as a novel nanomaterial

Abstract The aim of this research is to control specific properties of nickel-phthalocyanine (NiPc) thin film by doping with tin (Sn). The hybrid thin films, Sn-doped NiPc, were fabricated by thermal co-evaporation as a function of Sn concentration. The quantity of Sn in NiPc matrix was controlled via the different deposition rate between Sn and NiPc. The specific properties of the hybrid films, e.g. morphology, optical absorption, chemical bonding as well as electrical characteristics of the devices used such hybrid material as an active layer were characterized by combinations of microscopic and spectroscopic techniques. The experimental results evidently present the modification of thin film properties by adding Sn into NiPc matrix, i.e. the change of morphology from granules to fibers, the increase of beta-phase formation in the films as well as the enhancement of electrical properties resulting from the increase of both charge carrier mobility and carrier concentration in the hybrid material. Moreover, the internal formation of the Sn-doped NiPc reveals that Sn dopants are embedded in the NiPc matrix as Sn metal clusters coated with derivative metal oxide of Sn (SnOx). This research demonstrates that the doping metal-phthalocyanine with metal is an alternative approach to control the specific properties that possibly suit for organic electronic applications.

Growth and Characterizations of Tin-Doped on Nickel-Phthalocyanine as a Novel Nanomaterial

Tin-doped nickel phthalocyanine thin films (Sn-doped NiPc) were deposited by thermal co-evaporation method. Doping concentration of tin in NiPc was controlled via different deposition rates between metal dopent and host organic material. Properties of the thin films doped by tin in the range of 3 to 15% were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS). Furthermore, electrical properties of Al/Sn-doped-NiPc/ITO devices i.e. charge carrier concentration and carrier mobility were characterized by current-voltage and capacitance-voltage measurements. Microscopic results show clear evidence of the morphological transition from granular structure in undoped-film to rod-liked structure in the films doped more than 5%. Moreover, surface grain size exhibits the tendency to decrease with the increase of doping concentration. Optical properties reveal that the packing of NiPc molecules in all doping conditions is the combination of α-phase (majority) and β-phase (minority). However, evolution of β-phase NiPc is observed with the increase of doping concentration. Photoelectron analyses indicate shift of binding energy in both Ni2p and Sn3d levels corresponding to charge transfer between nickel-core and tin dopant. In addition, the electrical properties show the enhancement of the film’s conductivity due to the increase of charge carrier concentration with the higher Sn-doping level.

Nickel phthalocyanine based organic photo transistor: effect of semiconductor film thickness

Organic semiconducting photo transistors have been fabricated by depositing nickel phthalocyanine (NiPc) and semitransparent thin films of aluminum in sequence by vacuum evaporation on a glass substrate having silver source and drain electrodes. The thickness of NiPc film has been varied as 100 nm, 200 nm and 300 nm. The fabricated organic photo transistors (OPTs) having metal (aluminum)-semiconductor (NiPc) Schottky junction are then characterized and the effects of light irradiation on its characteristics have been investigated. It is observed that the drain current of OPTs rises with increasing radiation intensity and the OPTs having 200 nm thick NiPc film exhibited better performance as compared to the transistors having 100 nm and 300 nm thick films of NiPc.

Investigation of structural and optoelectronic properties of annealed nickel phthalocyanine thin films

Thin films of nickel phthalocyanine (NiPc) were prepared by thermal evaporation and the effects of annealing temperature on the structural and optical properties of the samples were studied using different analytical methods. Structural analysis showed that the grain size and crystallinity of NiPc films improved as annealing temperature increased from 25 to 150°C. Also, maximum grain size (71.3nm) was obtained at 150°C annealing temperature. In addition, NiPc films annealed at 150°C had a very smooth surface with an RMS roughness of 0.41nm. Optical analysis indicated that band gap energy of films at different annealing temperatures varied in the range of 3.22–3.28eV. Schottky diode solar cells with a structure of ITO/PEDOT:PSS/NiPc/Al were fabricated. Measurement of the dark current density–voltage (J–V) characteristics of diodes showed that the current density of films annealed at 150°C for a given bias was greater than that of other films. Furthermore, the films revealed the highest rectification ratio (23.1) and lowest barrier height (0.84eV) demonstrating, respectively, 23% and 11% increase compared with those of the deposited NiPc films. Meanwhile, photoconversion behavior of films annealed at 150°C under illumination showed the highest short circuit current density (0.070mA/cm2) and open circuit voltage of (0.55V).

Hole Doping Through Indium Intercalation Into Nickel Phthalocyanine

A new intercalation of indium and nickel phthalocyanine(NiPc) thin films is developed by using thermal co-evaporation technique. X-ray diffractometer(XRD) and optical absorption spectroscopy of In-doped NiPc suggest the crystal structure of In-doped NiPc is α-phase as same as that of pristine NiPc. Current-voltage characteristic of Shottky diode fabricated with In-doped NiPc thin film shows the enhancement of charge carrier concentration due to indium doping. Further photoelectron spectroscopy experiments prove that In-doped NiPc is hole transport material.

DC AND AC MEASUREMENTS ON ITO/NIPC/METAL CELLS IN HUMID ENVIRONMENT

Current density-vs-voltage characteristics and frequency dependences of impedance were analyzed for sandwich cells ITO/NiPc/Metal, where ITO is a transparent conducting double indium-tin oxide, NiPc is a thermally evaporated nickel phthalocyanine thin film, and Metal is aluminum or indium top electrode. After testing in dry air, these cells were exposed to saturated water vapors, or mixed water/ammonia vapors with different pressures. Comparative analysis of the data taken from DC and AC measurements in the dark was carried out. Contributions of the NiPc film bulk and the NiPc/Metal interfacial region to conducting properties of the cells were elucidated. Impedance of the cells in various environments was interpreted using equivalent circuits, and the time scales for relaxation processes in NiPc films were thus estimated.

Structural and Surface Morphology Analysis of Nickel Phthalocyanine Thin Films

The thin films of Nickel Phthalocyanine (NiPc) on glass substrates were prepared by vacuum evaporation at different substrates temperatures (300, 325, 350, 400, 450) K. The structure and surface morphology of NiPc in powder and thin film forms (265 nm) were studied using X-ray diffraction and atomic force microscope (AFM), and showed that there was a change and enhance in the crystallinity and surface morphology due to change in the substrates temperatures. Analysis of X-rays diffraction patterns of NiPc in powder form showed that it had an α-polycrystalline phase with monoclinic system with lattice constants a = 1.513 nm, b = 0.462 nm, c = 2.03 nm and β = 123.46°. Thermal evaporation of NiPc at different substrates temperatures led to β-crystalline films oriented preferentially to the (100) plane with different substrate temperatures. The mean crystallite size increased with substrates temperatures from 300 K to 450 K. This result was supported by AFM measurements, which exhibited a relatively larger grain size.

Experimental and density functional theoretical study of the effects of chemical vapours on the vibrational spectra of nickel phthalocyanine thin films

Abstract We report the effects of chemical vapours on the Raman and infrared absorption spectra of α crystalline nickel phthalocyanine thin films. Transmission electron micrograph of the thin films suggests presence of nano-sized particles of nickel phthalocyanine in the thin film. Some vibrational bands show changes in their positions and/or intensities on exposure of thin films with chemical vapours. These changes have been interpreted on the basis of interactions of the vapours molecule with the central nickel ion and other peripheral atoms of the phthalocyanine ring. Density functional theory (DFT) calculations have been carried out to determine the probable geometric structures of the complexes of vapour and phthalocyanine molecules. Calculated geometric structures show in-plane and out-of-plane distortions in the phthalocyanine molecule. Calculations further suggest charge transfer between vapour and phthalocyanine molecules.

Hybrid Materials from Carbon Nanotubes, Nickel Phthalocyanine, and Polymer Thin Films for the Electrochemical Oxidation of Nitric Oxide in Solution

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Study of Barrier Structures on the Base of Nickel Phthalocyanine Thin Films During the Interaction with the Ammonia Medium

Thin films of the α polymorphic modification of a nickel phthalocyanine (NiPc) which possess a high sensitivity to actions of gaseous media are deposited by the thermal vacuum deposition method. Indium tin oxide (ITO) continuous thin films on glass are used as substrates. On the basis of these films, the barrier structure ITO/NiPc/Al has been formed. We have found that there exists the electrogeneration effect in the ITO/NiPc/Al structure under the action of the gaseous ammonia medium. The appearance of a short circuit current and an open circuit voltage is observed only in the ITO/NiPc/Al structures that can be explained by redox reactions.

Electronic structure investigation of nickel phthalocyanine thin film interfaces with inorganic and organic substrates

AbstractThe interfacial electronic properties of ultra thin films of Nickel Phthalocyanine (NiPc) on inorganic (polycrystalline Au and Ag, sputtered‐ITO) as well as organic (PEDOT:PSS) substrates were compared. The formation of the interfaces was studied by X‐ray and Ultra‐Violet Photoelectron Spectroscopies (XPS, UPS). From the experimental results, information about the interfacial chemistry, band bending in the organic semiconductor and interfacial dipoles was deduced. The valence band structure, the HOMO position and the work function of the NiPc were also determined. The hole injection barrier at the interface was obtained for all substrates and the energy band diagrams were traced in all cases. A Fermi level alignment was found in the interfaces with inorganic substrates, whereas a pinning of the Fermi level was observed with the organic substrate resulting in a significant decrease of the hole injection barrier. All systems investigated divert from the Schottky‐Mott rule and the observed interfacial dipoles appear to increase as the work function value of the substrate increases. The present study shows the importance of the chemical character of the substrate in the electronic properties of the interfaces with an organic semiconductor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)