Orange Dye Thin Film Resistive Hygrometers

An investigation on electrical properties of organic semiconductor, Orange Dye (OD), C17H17N5O2, resistive hygrometers was made in present study. Organic thin films were deposited on substrate by different thin film deposition methods, such as by vacuum evaporation method (Aluminum/Orange Dye/Aluminum), by spin-coater method from solution (Gold/Orange Dye/Gold), and in normal gravity condition by placing drops of OD solutions over the surface of tissue paper (Tin metal/Orange Dye in tissue paper/Net metal). As OD is also temperature sensitive, that is why to compensate temperature effect for the measurement of humidity dependent electrical properties, special arrangement was provided over the same substrate, but encapsulated from humidity environment. The AC (frequency of 10 Hz) and DC resistances were evaluated from current-voltage characteristics of all samples of resistive hygrometers, measured in the temperature interval range of 20-70 °C and relative humidity range of 30-80%. It was observed that the resistance of the OD decreases with a rise in temperature. Similarly, OD resistance is observed to decrease with increase in humidity level. The relative resistance ratio to relative humidity was found 30 and 12 for the samples deposited by vacuum evaporation and from solution by spin coater respectively. Humidity dependent on electrical properties of these resistive hygrometer make them attractive for use in development of industrial humidity meters

Electrical Properties of Organic Semiconductor Orange Nitrogen Dye Thin Films Deposited from Solution at High Gravity

In this study the electrical properties of organic semiconductor orange nitrogen dye (OND) have been examined. Thin film samples were deposited from OND solution in water on a nickel substrate (it was the first electrode) at room temperature at different gravity conditions including, 1 g (reference samples), 123 g, 277 g and 1107 g by a centrifugal machine. As a second electrode of the samples a gallium drop was used. The voltage-current characteristics of the samples were measured at temperature interval of 30 °C 60 °C. It was found that all voltage-current characteristics were asymmetrical with slightly rectification behavior. The resistances of the samples decrease monotonously with temperature but with acceleration they show minimum around of 123 g. As a rule the forward bias resistance (+ voltage was applied to gallium) were less than reverse bias ones (+ voltage was applied to nickel). The electric behavior of the samples analyzed by the conception of space-charge limited currents (SCLC) at the presence of two different kinds of metallic electrodes (Ni and Ga) in the samples

Copper Phthalocyanine Surface-type Photocapacitive Sensor

In this study the photocapacitive behavior of organic semiconductor, photosensitive material copper phthalocyanine (CuPc) were investigated. Thin film of the copper phthalocyanine was deposited by vacuum evaporation on glass substrate with silver surface-type electrodes and Ag/CuPc/Ag photo capacitive sensor was fabricated. It was shown that under filament lamp illumination up to 1000 lx the capacitance of the Ag/ CuPc/Ag photo capacitive sensor increased continuously up to 20% with respect of dark condition. It is assumed that photo capacitive response of the sensor is associated with polarization due to the transfer of photo-generated electrons and holes

On Physical Vapor Deposition of Organic Semiconductor CuPc Thin Films in High Gravity

Thin organic films of p-type semiconductor copper phthalocyanine (CuPc, C32H16N8Cu) deposited by vacuum evaporation on glass substrates at different gravity conditions, from 50 g to –50 g (g – denotes the terrestrial gravity acceleration) in a centrifugal machine, were investigated. Thickness distribution of the film deposited was determined by measurement of absorbance using a scanning light beam probe. An anisotropic distribution of the film was observed in the direction of source and substrate rotation. The anisotropy is associated with centrifugal motion of the source-substrate system. In a direction perpendicular to the rotation, the deposition distribution was isotropic and obeyed, in principle, the theoretical approach which requires a maximum deposition in the centre of the sample. The experimentally observed influence of the acceleration on the deposition rate of the CuPc films on the substrate was simulated

Electrical Properties of Poly-N-Epoxypropylcarbazole/Vanadium Pentoxide Composite

In the present work the electrical properties of poly-N-epoxypropylcarbazole (PEPC) and vanadium pentoxide (V2O5) composite have been studied. The composite was formed by mixing of PEPC solution in benzene with V2O5 powder and stirring at room temperature. The composite solution was deposited on a dielectric substrate with copper electrodes and the Cu/PEPC-V2O5/Cu surface type film samples were fabricated. The Cu/V2O5/Cu samples were used as a reference where the films were deposited from the mixture of V2O5 powder in distilled water. Resistance-temperature relationship and voltage-current characteristics of the composite and V2O5 samples were studied by using conventional digital voltmeter and ammeter in the temperature range of 27-110 °C with an error of ±0.5%. It was observed that the DC electrical conductivity, activation energy and non-linearity of voltage-current characteristics of the samples are temperature dependent. It was found that the temperature dependence of electrical conductivity of the V2O5 samples on the whole obeys T-1/4 law whereas the PEPC-V2O5 ones show visible deviations from that. The PEPC-V2O5 samples may be used as thermistors as the temperature coefficient of their resistance is large and at 27 °C is equal to -4.7%/°C

Copper phthalocyanine and metal free phthalocyanine bulk heterojunction photodetector

In this study we present the dependence of electrical properties of copper phthalocyanine (CuPc) and metal free phthalocyanine (H2Pc) bulk heterojunction structure under different illumination levels. To fabricate the device on ITO coated glass substrate the bulk heterojunction thin film of CuPc and H2Pc with thickness varying from 100nm to 300nm are deposited by thermal evaporator. Aluminum thin film was deposited by thermal evaporation as a top contact. The optical properties of the fabricated device are investigated using UV–vis spectroscopy. The current-voltage characteristics in dark and under illumination show that the device is sensitive towards visible light. The absorption spectrum describes its photo sensitivity in the range of wavelength from 200nm to 850nm. Simulation of current-intensity of light curve is carried out and experimental results are found in good agreement with simulated ones