Phthalocyanine LB Research Articles

Conductometric gas sensing studies of tert-butyl silicon-[bis ethyloxy]-phthalocyanine LB films

Ultrathin Langmuir-Blodgett film properties of tert-butyl silicon-[bis ethyloxy]-phthalocyanine (tbPcSi(OC2 H5)2) have been studied and characterised. Surface pressure–area isotherms reveal an area per molecule of around 0.85 nm2, and that a compact ‘solid’ phase occurs in the region 10–30 m N m−1. LB films of different thicknesses were deposited onto gold interdigitated electrodes on glass in order to facilitate I–V measurements and assess the conductometric sensing properties in response to 5 ppm NO2. The I–V characteristic is Ohmic and yields conductivity in the range comparable to that obtained for other phthalocyanine monomers. The gas sensing behaviour of these films in response to NO2 was investigated and modelled using a double exponential model. Preliminary UV–visible spectroscopic investigations indicate that the film also responds optically.

Characterisation and gas sensing properties of tert-butyl silicon-[bis ethyloxy]-phthalocyanine LB films

An ultrathin Langmuir–Blodgett film of tert-butyl silicon-[bis ethyloxy]-phthalocyanine (tbPcSi(OC 2H 5) 2) has been investigated as an interesting candidate for the detection of nitrogen dioxide gas at a concentration of 5 ppm (by volume). Surface-pressure area isotherms reveal an area per molecule of around 80 Å 2 and that a compact ‘solid’ phase occurs in the region 10–30 mN m −1. Five layer LB films were deposited onto gold interdigitated electrodes on glass in order to facilitate I– V measurements and assess the conductometric sensing properties in response to 5 ppm NO 2. The I– V characteristic is Ohmic and yields a conductivity in the range 3.4 × 10 −6 to 5.9 × 10 −6 (Ω cm) −1 which is comparable to that obtained for other phthalocyanine monomers. Exposing the LB films to NO 2 results in an increase in current (for a 5 V bias) by a factor of 8 and a response time ( t 50) of approximately 200 s. Preliminary UV–vis spectroscopic investigations indicate that the film also responds optically.

Preparation and Configuration of Copper Phthalocyanine LB Films

Preparation and Configuration of Copper Phthalocyanine LB Films

Temperature characteristics of optical parameters of phthalocyanine LB films and spin-coated films

The LB films and spin-coated films of tetra-neopentoxy phthalocyanine zinc (TNPPcZn) were prepared and annealed at different temperatures. Their refractive index (n) and extinction coefficient (k) were measured by p-polarized reflectance. The similar value of n and k, as well as similar changing tendency of it and k at varied annealing temperatures, was found between LB films and spin-coated films. In addition, the absorption curves of TNPPcZn LB films and spin-coated films in visible range at different annealing temperature were investigated. The results indicate that the changing tendency of the extinction coefficient of two kinds of TNPPcZn films obtained from two methods mentioned above were coincident. When the annealing temperature increased to 150 degrees C, the monomers of TNPPcZn films transformed to aggregates, n(f) and k(f) of the films increased. Further, n(f) and k(f) decreased as aggregates changed back to monomers again at the annealing temperature of 300 degrees C. The experimental results coincide well with the theoretical analysis. (C) 2004 Elsevier B.V. All rights reserved.

Preparation of Langmuir-Blodget Films of Phthalocyanines and Investigation by Atomic Force Microscope

The Langmiure-Blodget monolayer films of five solvent-soluable phthalocyanines, bis-(benzyloxy) phthalocyaninatosilicon. bis-(p-chlorophenoxy) phthalocyaninatosilicon, bis-(p-chlorophnoxy) (tetra-4-nitrophthalocyaninato)silicon, bis-(p-bromophenoxy) naphthalocyaninatosilicon, propoxy-(tetra-4-nathalenoxypthalocyaninato)aluminium have been prepared by using Langmiure-Blodget techniques and their surface properties have been studied. When phthalocyanines dyes with no peripheral substituents were spread on a subphase of water to form LB film, the molecular state of LB film changed form G(gaseous) film into L 2 (liquid condensed) film and finally into multi-layer film (crinkled). The π-A isotherms of phthalocyanine LB film depended deeply on the molecular structure, especially on the phthalocyanine ring and substituted groups. The morphology of the LB film was investigated by AFM (atomic force microscope) analysis. It was shown that domains of dye molecules formed on the LB film. Five phthalocyanine dyes gave different morphology domains which the forms, sizes, arrangement, orientation and distribution were related to molecular structure and dipping condition.

The influence of heat-pretreatment on the gas-sensing properties of novel zinc phthalocyanine LB films

A novel asymmetrically substituted amphiphilic phthalocyanine, 1,4-di(2-hydroxyethoxyl)-8,9,16,17,23,24-hexapentyloxylphthalocyaninozinc ( asy - PcZn ), was synthesized. It can be deposited as well-ordered LB films. Significant structural changes of the films were observed by UV-vis absorption spectra and low-angle X-ray diffraction after the films were annealed at 150 °C. What is more interesting is that the initial conductance of the films in air decreases and the response signal to NH 3 is weaker with longer response time after annealing compared with that of the unpretreated films.

OLED with Two Types of Double Buffer Layers Composed of Phthalocyanine LB Films

OLED with Two Types of Double Buffer Layers Composed of Phthalocyanine LB Films

A Novel Amphiphilic Zinc Phthalocyanine LB Flms as Gas Sensor Material and its Interaction with NH3

Two kinds of amphiphilic phthalocyanines(AmPc,AmPcZn) have been deposited as smooth and well ordered LB films. Absorption spectra show that AmPc films are consistent with a stacked cofacial columnar structure while the AmPcZn films consist of aggregates with weakly interacting molecules. These two films exhibit different behavior toward NH3 gas-sensing. AmPcZn films gave strong and fast response on exposure to NH3 whereas AmPc films showed very weak response. It is proposed that coordination of NH3 by AmPcZn results in lowering the energy gap and hence the activation energy of AmpcZn that account for the larger increase in conductance of AmpcZn films compared with AmPc films.

The Annealing and Photoelectric Properties of Phthalocyanine LB Films

The Annealing and Photoelectric Properties of Phthalocyanine LB Films

The characterization and gas-sensing properties of a novel amphiphilic phthalocyanine LB film

The LB films of asymmetrically substituted 1,4-di(hydroxyethoxy)-9,10,16,17,23,24-hexapentyloxyphthalocyanine have been fabricated at different surface-pressures. The molecular packing of the films has been characterized by polarized UV-vis. absorption spectroscopy and low angle X-ray diffraction methods. The results show that the films have well-ordered structure and the molecular packing within the films is dependent on the film-deposition conditions such as surface-pressure. The gas-sensing behavior of the films to NO 2 gas has been investigated by conductance measurements. It is indicated that the films deposited at lower surface-pressure show larger and faster response and recovery kinetics.

Direct observation of the stacked structure in substituted copper phthalocyanine LB films with STM

AbstractThe in‐plane molecular structures of octa‐alkyl substituted copper phthalocyanine LB films deposited on graphite have been resolved with a scanning tunnelling microscope (STM). The face‐to‐face stacking of Pc macrocycles has been observed in the topographies of R8PcCu monolayers. The stacking period was found to be 3.8–4 Å and the molecular rows were separated by 19 Å and 16 A for (C6H13)PcCu and (C5H11)PcCu respectively.

Electroluminescent characteristics of fluorometric yellow/ phthalocyanine LB film

Three types of organic electroluminescence (EL) cell structures, among which, two types consisting of fluorometrie yellow (FY) as emitting layer and copper phthalocyanine (CuPc) as hole transport layer, were fabricated. The EL mecharism were studied by comparing the transpsort characteristics of the CuPc films made of LB and vacuum deposition methods.

Ordered Langmuir-Blodgett films of a substituted lutetium bisphthalocyanine

High-quality LB multilayers have been prepared from the Lu(III) sandwich complex of 2,3,9,10,16,17,23,24-octa ( n-butoxy)phthalocyanine (LuPc 2(OBu) 16). Surface pressure-area isotherms were characterized and indicate that a stable monolayer is formed corresponding to an area per molecule of 2.4 nm 2 at 30 mN m −1. The LB films were highly birefringent, and polarized spectra gave dichroic ratios of 3.3 for the 670 nm absorption band and between 0.5 and 2.8 for infrared absorptions. The results indicate that the phthalocyanine rings were highly oriented perpendicular to the dipping direction but somewhat tilted from the substrate normal. The order was shown to be absent when (i) unsubstituted LuPc 2 was used for LB films, or (ii) the horizontal lifting method of film deposition was used, or (iii) the surface pressure was increased to 50 mN m −1, causing a molecular rearrangement. The ordering was improved at 100 °C and finally lost at 280 °C by annealing on a hot stage. The d.c. electrical conductivity of LB films of LuPc 2(OBu) 16 was low (σ ≈ 2 × 10 −7 Ω −1 m −1), in contrast with unsubstituted LuPc 2 (σ ≈ 10 −1 Ω −1 m −1) and showed no evidence for anisotropy. The findings are in broad agreement with related studies and illustrate some of the many factors involved in improving the structure of phthalocyanine LB films for possible applications.

SERRS of Phthalocyanine Derivatives LB Monolayer

SERRS of copper tetrakis(2,4-ditert-penthyl phenoxy) Phthalocyanine LB monolayer on Ag island film and RRS of the compound in solid state have been obtained. On comparison between the spectra, it is proposed that the macrocycle of the molecule on the Ag substrate is oriented parallel to the surface.

Blue electroluminescence from ZnSe/Langmuir-Blodgett film MIS diodes

We report for the first time, the electrical and electroluminescent properties of Au/substituted silicon phthalocyanine LB film/MOCVD ZnSe MIS diodes. Underforward bias, and at room temperature the devices exhibited blue-white electroluminescence. Further investigation revealed two peaks in the spectrum. The 460nm peak coincides with the maximum output in the PL spectrum and is attributed to band-to-band recombination.