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1 – 10 of over 1000Khasan S. Karimov, Zubair Ahmad, Noshin Fatima, Muhammad Mansoor Ahmed and Muhammad Abid
The paper aims to study the effects of humidity on the electrical properties of copper phthalocyanine (CuPc) thin films deposited at different gravity conditions.
Abstract
Purpose
The paper aims to study the effects of humidity on the electrical properties of copper phthalocyanine (CuPc) thin films deposited at different gravity conditions.
Design/methodology/approach
Surface-type samples were fabricated on glass substrates with preliminary-deposited copper electrodes. The CuPc solution was prepared in benzene. The thin films of CuPc were deposited on these substrates at diverse gravity conditions by drop-casting and centrifugation at 1 × g and 70 × g, respectively. Impedance and capacitance of the fabricated devices were measured against the different relative humidity ranging from 32 to 98 per cent.
Findings
The impedance and the capacitance of the CuPc film were found to be dependent on the ambient humidity levels (32-98 per cent) and the gravity conditions (1 × g and 70 × g) opted during the fabrication process.
Research limitations/implications
The centrifugation technique can potentially be used in the instrumentation industry for the fabrication of humidity sensors.
Practical implications
The results of the investigations can potentially be used in the instrumentation and optoelectronics industry for the fabrication of humidity sensors.
Originality/value
CuPc films were deposited from a solution in benzene using drop-casting and centrifugation. The electrical properties of the films were found to be dependent on film fabrication conditions and ambient humidity levels. Growth-dependent electrical properties of the CuPc films can be explained by considering their structure.
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This paper aims to discuss the new applications enabled by printed sensors.
Abstract
Purpose
This paper aims to discuss the new applications enabled by printed sensors.
Design/methodology/approach
The paper discusses how silicon‐based sensors are manufactured using the time‐consuming, expensive, and complicated fabrication process of traditional semiconductor devices and shows what is needed in order to produce such new devices with the advantages of printed sensors.
Findings
With new materials, new processing technologies and a new manufacturing process, thin, flexible, lightweight, cost‐effective sensors are made possible through the power of printed semiconductors.
Originality/value
This paper should be of value in terms of understanding the pros of printed semiconductors and the resulting sensors which have a number of unique mechanical, electrical, and optical properties.
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F. Aziz, K. Sulaiman, Wissam Khayer Al-Rawi, Z. Ahmad, M.H. Sayyad, Kh. S. Karimov, L.L. Wei and M. Tahir
The purpose of this paper is to investigate the effect of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on improvement of physical and electrical properties of vanadyl…
Abstract
Purpose
The purpose of this paper is to investigate the effect of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on improvement of physical and electrical properties of vanadyl phthalocyanine derivative. The correlation between the physical characteristics of the active layers, comprising vanadyl 2,9,16, 23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO) and PCBM, and the electrical properties of metal/organic/metal devices have been studied. The use of soluble vanadyl phthalocyanine derivative makes it very attractive for a variety of applications due to its tunable properties and high solubility.
Design/methodology/approach
The sandwich type structures Al/VOPcPhO/Al and Al/VOPcPhO:PCBM/Al were fabricated by spin casting the active organic layers between the top and bottom (aluminum) electrodes. The stand-alone (VOPcPhO) and composite (VOPcPhO:PCBM) thin films were characterized by X-ray diffraction, atomic force microscopy, UV/Vis and Raman spectroscopy. The electronic properties of the metal/organic/metal devices were studied using current-voltage (I-V) characteristics in dark at room temperature.
Findings
The values of barrier height for Al/VOPcPhO/Al and Al/VOPcPhO:PCBM/Al devices were obtained from the forward bias I-V curves and were found to be 0.7 eV and 0.62 eV, respectively. The present study indicates that the device employing VOPcPhO:PCBM composite film as the active layer, with better structural and morphological characteristics, results in reduced barrier height at the metal-organic film interface as compared to the one fabricated with the stand-alone film.
Research limitations/implications
It is shown that doping VOPcPhO with PCBM improves the crystallinity, morphology and junction properties.
Practical implications
The spin coating technique provides a simple, less expensive and effective approach for preparing thin films. The soluble VOPcPhO is conveniently dissolved in a number of organic solvents.
Originality/value
The physical properties of the VOPcPhO:PCBM composite thin film and the electrical properties of the composite thin-film-based metal/organic/metal devices have not been reported in the literature, as far as our knowledge is concerned.
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F. Aziz, Z. Ahmad, S.M. Abdullah, K. Sulaiman and M.H. Sayyad
The purpose of this paper is to study the optical and electrical characteristics of a single-junction solar cell based on a green-colour dye vanadyl 2,9,16, 23-tetraphenoxy-29H…
Abstract
Purpose
The purpose of this paper is to study the optical and electrical characteristics of a single-junction solar cell based on a green-colour dye vanadyl 2,9,16, 23-tetraphenoxy-29H, 31H-phthalocyanine (VOPcPhO). The use of soluble vanadyl phthalocyanine derivative makes it very attractive for photovoltaic applications due to its tunable properties and high solubility.
Design/methodology/approach
A photoactive layer of VOPcPhO has been sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes to produce a ITO/PEDOT:PSS/VOPcPhO/Al photovoltaic device. The VOPcPhO thin film is deposited by a simple spin coating technique. To obtain the optimal thickness for the solar cell device, different thicknesses of the photoactive layer, achieved by manipulating the spin rate, have been investigated.
Findings
The device exhibited photovoltaic effect with the values of Jsc, Voc and FF equal to 5.26 × 10-6 A/cm2, 0.621 V and 0.33, respectively. The electronic parameters of the cell have been obtained from the analysis of current-voltage characteristics measured in dark. The values of ideality factor and barrier height were found to be 2.69 and 0.416 eV, respectively. The optical examination showed that the material is sensitive to light in the UV region between 270 nm and 410 nm, as well as in the visible spectrum within the range of 630 nm and 750 nm.
Research limitations/implications
The solar cell based on a single layer of vanadyl phthalocyanine derivative results in low efficiency, which can be enhanced by introducing a variety of donor materials to form bulk heterojunction solar cells.
Practical implications
The spin coating technique provides a simple, less expensive and effective approach for preparing thin films.
Originality/value
A novel thin-film, single-junction organic solar cell, fabricated by using VOPcPhO, has been investigated for the first time ever. The vanadyl phthalocyanine derivative together with a donor material will have potential application for improved efficiency of the solar cells.
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Matteo Porro, Carlo de Falco, Maurizio Verri, Guglielmo Lanzani and Riccardo Sacco
The purpose of this paper is to develop a computational model for the simulation of heterojunction organic photovoltaic devices with a specific application to a light harvesting…
Abstract
Purpose
The purpose of this paper is to develop a computational model for the simulation of heterojunction organic photovoltaic devices with a specific application to a light harvesting capacitor (LHC) consisting of a double layer of organic materials connected in series with two insulating layers and an external resistive load.
Design/methodology/approach
The model is based on a coupled system of nonlinear partial and ordinary differential equations describing current flow throughout the external resistive load as the result of exciton generation in the bulk, exciton dissociation into bonded pairs at the acceptor-donor material interface, and electron/hole charge generation and drift-diffusion transport in the two device materials.
Findings
Numerical simulation results are shown to be in good agreement with measured on-off transient currents and allow for novel insight on the microscopical phenomena which affect the external LHC performance, in particular, the widely different time scales at which such phenomena occur and their relation to the overall device dynamics.
Originality/value
The LHC demonstrates the viability of a novel approach for converting light energy into an electric current without a steady state flow of free charge carriers through the semiconducting layers. The new insight about the microscopic working principles that determine the macroscopically observed behavior of the LHC obtained via the model proposed in this paper are expected to serve as a basis for studying techniques for exploiting the full potential of the LHC.
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