C.S Menon

Optical studies of manganese phthalocyanine thin films

Abstract Thin films of manganese phthalocyanine (MnPc) were sublimed onto glass substrates in high vacuum. Optical studies were done on MnPc films deposited at room temperature. The optical properties of monoclinic forms are reported here. Optical parameters were calculated from the absorption spectra over the wavelength range 250–900 nm. The optical band gap, absorption coefficient and extinction coefficient of MnPc thin films for various thicknesses were calculated. Also, the relation between the absorption coefficient and the extinction coefficient with photon energy were plotted.

Estimation of the refractive index and dielectric constants of magnesium phthalocyanine thin films from its optical studies

Abstract Magnesium phthalocyanine thin films are prepared at room temperature by vacuum sublimation . The optical absorption and reflectance spectra of the films are studied. The absorption co-efficient α, and the extinction co-efficient κ, are directly found from the spectral data. Graph of α2 vs. hν is plotted and the optical band gap of the material is calculated. Using α and κ, the refractive index n, the real and imaginary parts of the dielectric constant viz. e1 and e2 are also determined.

Determination of the thermal activation energy and grain size of iron phthalocyanine thin films

Electrical and structural properties of iron phthalocyanine (FePc) thin films deposited onto glass substrates are studied as a function of substrate temperature and post-deposition annealing. Arrhenius plot yields thermal activation energy in the intrinsic region and impurity scattering region. X-ray diffraction pattern is used to find the average microcrystalline grain size using Scherrers formula. Films prepared at lower substrate temperature and annealed in air at lower temperature are identified to be of α-phase with preferential orientation along (200) direction.

Determination of the energy band gap of thin films of cadmium sulphide, copper phthalocyanine and hybrid cadmium sulphide/copper phthalocyanine from its optical studies

Abstract Cadmium sulphide (CdS) thin films are prepared onto glass substrates by chemical bath deposition technique (CBD). Thin films of copper phthalocyanine (CuPc) are also sublimed onto glass substrates in high vacuum at room temperature. Hybrid CdS/CuPc (organic–inorganic) thin films are obtained from CdS films grown on glass substrates by CBD technique and subsequently vacuum subliming CuPc onto them. These films are annealed in air at different temperatures. Optical studies are separately done on CdS, CuPc and hybrid CdS/CuPc thin films. Optical properties are studied (between 300 and 900 nm) in a UV–VIS Spectrophotometer and the absorbance recorded as a function of photon energy. The optical band gap and maximum absorption coefficient of the as-deposited and annealed samples are determined.

Electrical, optical and structural studies on nickel phthalocyanine thin films

Vacuum-sublimed thin films of nickel phthalocyanine were prepared. Post-evaporation annealing was done at temperatures of 323, 373, 423 and 473 K. The electrical conductivity and optical absorption spectra of these films were studied. Their structure and grain size have been determined.

Effect of air annealing on the electrical and optical properties of MgPc thin films

Electrical and optical properties of thermally evaporated air-annealed magnesium phthalocyanine (MgPc) thin films are studied. Thermal activation energy is calculated from the Arrhenius plot and in the intrinsic region, it is found to increase with the temperature up to 200 °C and decreases to a low value at 250 °C. Narrowing of band gap is observed with annealing temperature.

Determination of the thermal activation energy and optical band gap of cobalt phthalocyanine thin films

Thin films of cobalt phthalocyanine (CoPc) were prepared by vacuum evaporation of cobalt phthalocyanine powder at a pressure of 10−5 Torr. Silver electrodes act as ohmic contacts for electrical connections. Films were annealed at 50, 100, 150 and 200°C. The electrical conductivity studies were done in vacuum (<10−3 Torr). The UV-visible spectra were recorded and the optical band gap determined. The variation of the optical band gap with annealing temperature was determined. The effect of annealing on thermal activation energy is also reported in this paper.

Device preparation and characteristics of CuPc transistor

Static and dynamic characteristics of an organic static induction transistor (SIT) fabricated using copper phthalocyanine (CuPc) thin films are reported. Layered structure using CuPc as active layer consists of Al (drain)/CuPc/Al (gate)/CuPc/FTO (source)/glass. Electrical characteristics obtained are excellent at low negative gate voltages.

Photoconductivity measurements in lead phthalocyanine thin films

Abstract Lead phthalocyanine thin films (PbPc) were prepared by vacuum sublimation under a pressure of 10 −5 Torr. Photoconductive studies as a function of applied voltage, intensity of incident light, temperature and wavelength were carried out. Photocurrent spectra as a function of wavelength indicate peaks around 1.54, 1.98, 2.4, 3.0 and 3.48 eV. These are interpreted as transitions at critical points. From the temperature dependence of photoconductivity measurements, the activation energies 0.074 and 0.46 eV were obtained and 0.68 and 0.46 eV for dark conductivity. The dependence of the intensity of photocurrent yields a slope of m =0.6, in the photoconductivity equation I ph ∝(In) m . An energy level diagram is drawn for lead phthalocyanine thin films from the photoresponse studies.

Preparation and physical properties of CuPc substituted sodium borate glass matrix

Electrical conductivity and optical absorption of copper phthalocyanine (CuPc) substituted sodium borate glass is reported here for the first time. We have successfully prepared CuPc substituted sodium borate glass at 830 °C and some preliminary studies on this glass are reported. Activation energy and optical band gap were determined for the glass from the Arrhenius plot of conductivity and optical absorption spectra, respectively.