酞菁铜/金属薄膜界面电位与光二次谐波特性分析

Using the Kelvin probe and the optical second harmonic generation (SHG) measurement, the Space charged phenomenon and the non-linear optical effects at the interfaces of the coppertetra-tert-butyl phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal (AlorAu) coated glass slide substrate were in vestigated. The surface potentials decreaseas the film thickness increases and eventually approaches a saturated value. The SHG has been detected although there is a centro-symmetric systemin the Cuttb Pcmolecular, and avery strong SH signal can be investigated at 1260 nm band for Cuttb Pc/Al samples. According to a proposed physical model for Cuttb PcLB film/metal, the nonlinear mechanism were analyzed by using electromagnetic wave theory. It is considered that the enhanced SH peak of CuttbPc/Al is attributed to the strong surface potential aroused by SCIEF at the interface, and shows that the production of SH signal is correlated closely with the electrostatic phenomena at the interface.     

Second harmonic generation at the interface of copper tetra-tert-butyl phthalocyanine Langmuir-Blodgett film/metal

As one of the most primitive nonlinear optical phenomena, optical second harmonic genera-tion (SHG) has been investigated for half a century and it has become a very useful spectroscopic tool in the study of surface and interface[1—3]. It was theoretically shown that the SH signal cannot be generated in a centrosymmetric system. However, the generation of SH signal from the centro-symmetric molecules such as fullerene (C60) and CuPc has been detected[4—7]. In our recent ex-periments, an …     

酞菁铜化合物LB膜的制备及结构形态研究

利用LB技术研究了带有4个长碳氢链的酞菁铜化合物(CuC12Pc)的单分子膜及它与十八胺(ODA)、二十酸(AA)的混合LB膜的聚集结构形态. 结果表明这种酞菁铜化合物在气液界面上可以形成比较稳定有序的双层Langmuir膜, 且可以转移质量较好的多层LB膜. 利用原子力显微镜(AFM)研究了酞菁铜分子的聚集体结构, 发现CuC12Pc/AA混合膜表现为网状的聚集结构, 而CuC12Pc/ODA混合膜形成长岛颗粒状聚集, 并结合UV-Vis吸收光谱讨论了酞菁铜分子形成不同聚集结构的原因.     

Molecules of synthesized phthalocyanine as a material for the detection of 2,4-toluene diisocyanate (TDI)

Various numbers of LB monolayers of a metal-free phthalocyanine derivative, A410H₂Pc, have been deposited onto ultrasonically cleaned quartz substrates with platinum interdigitated electrodes. Similar devices i.e. those with the same number of LB layers, show the same response characteristics in the presence of 35 ppb (0.035 ppm) toluene diisocyanate (TDI)—a toxic substance used in the production of plastics and found in certain types of paint. The response times of the LB devices studied so far have been calculated to be about 40s. The electrical properties of evaporated films of a metal-free phthalocyanine derivative, α-H₂Pc, and those of the A410H₂Pc LB films have been found to be similar. The response time for the evaporated films has been found to be much less that that for the LB films. Although a direct comparison cannot be made between the LB and evaporated films, in this case, results suggest that devices fabricated from evaporated films will be much faster at detecting the presence of TDI than devices fabricated from LB films.     

Effects of Langmuir-Blodgett Film as Hole Transport Layer on Organic Electroluminescent Device Performance

Three types of organic electroluminescence(EL) cells with organic material FY as the EL-emitting layer and a copper phthalocyanine (CuPc) as the hole transport layer which were sandwiched between indium/tinoxde(ITO) and aluminum electrode have been fabricated by vacuum-vapor and Langmuir-Blodgett (LB) deposition:(a) ITO/FY/Al;(b)ITO/CuPc/FY/Al;(c) ITO/CuPc(LB)/FY/Al. It was found for the first time that the cell with the LB film as the hole transport layer has the highest luminescent intensity at the same bias-voltage. These results are attributed to the order orientation of the CuPc molecule in the layer of LB film.     

LB films of rodlike phthalocyanine aggregates: specular X-ray reflectivity studies of the effect of interface modification on coherence and microstructure

We present here X-ray specular reflectivity (XRR) characterization of the ordering of Langmuir-Blodgett films of the liquid crystalline phthalocyanine (Pc) 2,3,9,10,16,17,23,34-octakis(2-benzyloxyethoxy)copper(II) phthalocyanine, 1, on Si(100) wafers with a native oxide layer and these same substrates modified with monolayers of varying percentages of methyl- and phenyl-terminated silanes. The central copper atom in these Pc's provides for high contrast in X-ray reflectivity for single-bilayer films of 1. The XRR data are modeled as arising from multiple layers of organic material, above and below the rows of copper atoms in the aligned Pc cores; variations in the total thickness of these films, and the spacing between the rows of copper atoms, are attributed to changes in the interaction with the substrate, and changes in the Pc orientation and side chain packing. The most pronounced effect on these parameters comes from variations in the ratio of the phenyl-silane versus methyl-silane content of the substrate modifiers and annealing of these films past their crystalline (K) --> liquid crystalline (LC) mesophase transition temperature. Transfer of multiple bilayers of this Pc leads to additional changes in the thickness of each layer, eventually forming a hexagonal close-packed array, reminiscent of bulk fibers of this material, as revealed by X-ray diffraction (XRD).     

Dipole and charge effects of chloroaluminum phthalocyanine revealed by local work function measurements at sub-molecular level

Chloroaluminum phthalocyanine (ClAlPc), an important optoelectronic molecule with a permanent dipole moment pointing from the Pc ring to the ending Cl atom, adsorbed on Au(111) in either Cl-up or Cl-down configuration. Scanning tunneling microscopy/spectroscopy measurements revealed that at the centers of Cl-up and Cl-down molecules, the local work functions changed oppositely with respect to the Au(111) substrate. At their Pc lobes, however, the local work functions unanimously increased due to charging effect of the indole lobes in the ClAlPc molecule.     

用激光第二谐振光研究阴离子在多晶铜电极表面上的吸附

首次用激光产生的第二谐振光(SHG)检测到金属/水溶液界面上阴离子在多晶铜电极表面上的吸附,阴离子吸附特性对SHG强度影响明显,由多晶铜电极在(0.5-x)mol/L NaClO_4+xmol/L NaBr溶液中的SHG强度-电位曲线表明铜电极表面对ClO_4~-的吸附非常弱,对Br~-有特定的吸附,SHG强度随Br~-浓度增加而增强,结果表明SHG是定量研究电化学界面区吸附特性的灵敏有效的探针,可揭示金属与吸附质间相互作用的本质。     

Effect of peripheral hydrophobic alkoxy substitution on the organic field effect transistor performance of amphiphilic tris(phthalocyaninato) europium triple-decker complexes

A series of four amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with different lengths of hydrophobic alkoxy substituents on one outer phthalocyanine ligand [Pc(15C5)4]Eu[Pc(15C5)4]Eu[Pc(OCnH(2n+1))8] (n = 4, 6, 10,12) (1, 2, 4, and 5) was designed and prepared. Their film forming and organic field effect transistor properties have been systematically studied in comparison with analogous [Pc(15C5)4]Eu[Pc(15C5)4]Eu[Pc(OC8H17)8] (3). Experimental results showed that all these typical amphiphilic sandwich triple-decker molecules have been fabricated into highly ordered films by the Langmuir-Blodgett (LB) technique, which displays carrier mobility in the direction parallel to the aromatic phthalocyanine rings in the range of 0.0032-0.60 cm2 V(-1) s(-1) depending on the length of the hydrophobic alkoxy substituents. This is rationalized on the basis of comparative morphology analysis results of the LB films by the atomic force microscopy technique.     

Au∕CuPc interface: a valence band photoemission investigation

The formation of the metal-organic interface depositing gold, by thermal evaporation in ultrahigh vacuum conditions, onto a copper phthalocyanine film has been studied by means of ultraviolet photoemission spectroscopy. The evolution of the valence band spectra and in particular of the highest occupied molecular orbitals (HOMO) and of the Au upper states has been followed as a function of gold film thickness. The HOMO peak position is strongly influenced by the Au deposition, suggesting an n-doping process of the organic film. The gold 6s state behavior indicates the formation of small metal clusters whose size increases as a function of the gold deposited. The doping of the organic film determines a strong reduction of the film ionization energy.     

Role of coordinated metal ions on the orientation of phthalocyanine based coatings

In the present work, we have investigated the molecular orientation of phthalocyanine films deposited on polycrystalline gold. Three films built from the following molecules are investigated: phthalocyanine (H(2)Pc), cobalt phthalocyanine (CoPc) and copper phthalocyanine (CuPc). The films are prepared by spin coating and drop casting methods. Orientation analysis has been performed using polarization dependent Fourier transform infrared (FTIR) spectroscopy using transmission and grazing angle reflectance mode. The FTIR study suggests that each phthalocyanine film contains both alpha- and beta-phases. H(2)Pc based films demonstrate deposition method dependence on the molecular orientation, while the CuPc and CoPc films preserve their molecular orientation independent of deposition method. Grazing angle analysis also suggests that CoPc films show negligible preferred orientation irrespective of film deposition methods. In literature, the band at 878cm(-1) in CuPc has been assigned to out-of-plane bending of C-H. Our grazing angle experiments suggest that this band cannot be assigned to out-of-plane bending vibrations of C-H. Accurate band assignments are also described here for the phthalocyanine system.     

Vapour-growth of Sn on stearic acid molecular layers

Tin metal was vacuum deposited at room temperature on to Langmuir–Blodgett (LB) films with surfaces of either hydrophilic head groups or hydrophobic tail groups. Different growth modes on different surfaces of the LB films were observed with an atomic force microscope. Fine Sn particles deposited on the hydrophobic surface were uniform in size and similar in shape, but on the hydrophilic surface large Sn particles were observed. Chemical interactions between organic functional groups and deposited metal seems critical for the manner of crystal growth. The possibility of control over the crystallization of metals using two-dimensionally assembled organic molecules is demonstrated.     

油溶非对称取代酞菁铜的合成、表征及LB膜

本文以邻苯二甲酰亚胺为原料,合成了两种新的非对称取代酞菁铜配合物:4-(对羧基苯氧基)-三-4-(2,4-二特戊基苯氧基)酞菁铜(Ⅳ)和4-(邻氨基苯氧基)-三-4-(2,4-二特戊基苯氧基)酞菁铜(Ⅴ)。并经元素分析、红外光谱、核磁共振谱、质谱、顺磁共振谱及紫外光谱,对其结构进行了表征。两种配合物都易溶于二氯甲烷、氯仿和甲苯等有机溶剂,不溶于水。配合物的氯仿溶液能在水面上展开形成单分子膜。π-A曲线测定表明,配合物在亚相液面(水)上,随着表面压力的增大,膜面积连续不停地减少,有明显的“气”“固”变化过程,表明配合物能形成较好的LB膜。分子在膜中主要以倾斜的方式排列。以Z型累积方式沉积于金制梳状电极上的LB膜能导电,属于半导体材料,碘掺杂可改善膜的电导。膜电极的气敏特性研究发现,配合物对氨气有专一的气敏特性,氨气浓度为33ppm时即有响应,且灵敏度高。     

Thin-film transistors based on Langmuir-Blodgett films of heteroleptic bis(phthalocyaninato) rare earth complexes

An ordered molecular assembly of heteroleptic bis(phthalocyaninato) rare earth complexes M(Pc)[Pc(OC8H17)8] [M = Tb, Lu; H2Pc = phthalocyanine; H2Pc(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] has been fabricated by the Langmuir-Blodgett (LB) technique and characterized by surface pressure-area isotherms, electronic absorption and polarized electronic absorption spectroscopy, low-angle X-ray diffraction, and atomic force microscopy. The molecular ordering in the LB multilayer film on SiO2 substrate was made into a p-channel field effect transistor (FET), which was generally operated in the enhanced mode. The energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as the energy band diagram can be deduced from the electrochemical measurement results. The charge mobilities of Tb(Pc)[Pc(OC8H17)8] and Lu(Pc)[Pc(OC8H17)8] were calculated to be about 6.4 x 10(-4) and 1.7 x 10(-3) cm2 V(-1) s(-1), respectively.     

Dynamics of analyte binding onto a metallophthalocyanine: NO/FePc

The gas-surface reaction dynamics of NO impinging on an iron(II) phthalocyanine (FePc) monolayer were investigated using King and Wells sticking measurements. The initial sticking probability was measured as a function of both incident molecular beam energy (0.09-0.4 eV) and surface temperature (100-300 K). NO adsorption onto FePc saturates at 3% of a monolayer for all incident beam energies and surface temperatures, suggesting that the final chemisorption site is confined to the Fe metal centers. At low surface temperature and low incident beam energy, the initial sticking probability is 40% and decreases linearly with increasing beam energy and surface temperature. The results are consistent with the NO molecule sticking onto the FePc molecules via physisorption to the aromatics followed by diffusion to the Fe metal center, or precursor-mediated chemisorption. The adsorption mechanism of NO onto FePc was confirmed by control studies of NO sticking onto metal-free H2Pc, inert Au111, and reactive Al111.     

Facile electrochemical growth of nanostructured copper phthalocyanine thin film via simultaneous anodic oxidation of copper and dilithium phthalocyanine for photoelectrochemical hydrogen evolution

We present a novel electrochemical approach to grow copper phthalocyanine (CuPc) thin-film photoelectrodes through anodic oxidation of copper and dilithium phthalocyanine (Li₂Pc). This circumvents the challenges associated with the electrochemical processing of unsubstituted CuPc from solution. The potentiostatic co-electrooxidation reaction at the heterogeneous interface favors the growth of CuPc thin film. The surface morphology of thin film exhibits nanorod-like features. UV-Vis, grazing angle Fourier transform infrared (FTIR), and grazing angle X-ray diffraction patterns reveal that the nanocrystalline phase corresponds only to α-CuPc and no admixture of other polymorphs. Photocurrent measurement shows a stable photoresponse in neutral medium. The photoelectrochemical hydrogen evolution on p-type CuPc coated copper photocathode shows an enhanced activity over bare copper and indium tin oxide (ITO) electrodeposited with CuPc and monolithium phthalocyanine radical (LiPc) thin films.     

NO2 gas detection by Langmuir-Blodgett films of copper phthalocyanine multilayer structures

Copper (II) phthalocyanine derivatives with four alkyl chains were synthesized. Langmuir-Blodgett (LB) films of the following two compounds were deposited: Cu(II)[tetrakis(3,3-dimethyl-butoxycarbonyl)] phthalocyanine and Cu(II)[tetrakis(n-butoxycarbonyl)] phthalocyanine. Moreover, LB films from a 1:1 mixture of the two compounds were prepared. All isotherms and optical data were consistent with the molecules being stacked nearly edge-on to the substrate, with the molecular faces having a preferred orientation perpendicular to the dipping direction. The dynamic response characteristics of the electrical conductance of the LB films to different NO₂ concentrations in dry air are described. A relationship has been observed between the anisotropic molecular orientation and the electrical conductivity parallel to the substrate.     

Micro- and nanopatterned copper structures using directed self-assembly on templates fabricated from phase-separated mixed Langmuir-Blodgett films

We report a versatile method to confine metal thin films in micro- and nanopatterns using directed self-assembly on the templates fabricated from phase-separated mixed Langmuir-Blodgett (LB) films. The pattern of the mixed LB films can be tuned by adjusting intermolecular interaction between the film-forming molecules in the LB films and by varying the fabrication conditions of the films such as the mixing ratio, subphase temperature, and surface pressure. We use the patterned LB films for templates to confine metal in patterned regions, taking advantage of the difference between the surface free energy of the patterned regions and that of the self-assembled monolayer of the silane coupling agent. Au nanoparticles are confined onto the patterned films as a catalyst for the succeeding Cu electroless deposition. The atomic force microscopic images, Auger electron spectra, and scanning Auger electron maps of a Cu-deposited film show that Cu is selectively deposited on the patterns of phase separation of the original mixed LB films.     

Investigation of the mechanism of electroless deposition of copper on functionalized alkanethiolate self-assembled monolayers adsorbed on gold

We have investigated the reaction pathways involved in the unseeded electroless deposition of copper on self-assembled monolayers (SAMs) adsorbed on Au, using time-of-flight secondary ion mass spectrometry, optical microscopy, and scanning electron microscopy. At 22 degrees C copper deposits on both -CH3 and -COOH terminated SAMs. No copper deposition is observed on -OH terminated SAMs because the hydroxyl terminal groups react with formaldehyde in the plating solution, forming an acetal which prevents Cu deposition. At higher deposition temperatures (45 degrees C), no Cu is observed to deposit on -CH3 terminated SAMs because Cu2+ ions are not stabilized on the SAM surface. Copper complexes are still able to form with the -COOH terminal group at 45 degrees C, and so copper continues to be deposited on -COOH terminated SAMs. Copper also penetrates through -CH3 and -COOH terminated SAMs to the Au/S interface, suggesting that soft deposition techniques do not prevent the penetration of low-to-moderate reactivity metals through organic films.     

In-situ infrared spectroscopy of buried organic monolayers: influence of the substrate on titanium reactivity with a Langmuir-Blodgett film

The reactivity of metals vapor deposited onto organic monolayers has historically been correlated to the metal/terminal organic group chemistry. Here we demonstrate that the chemical composition of the substrate unexpectedly plays a significant role as well. In particular, the reactivity of evaporated titanium toward a cadmium stearate Langmuir-Blodgett (LB) film was found to depend on the substrate upon which the LB film was deposited. Infrared spectra taken in a modified ATR (Kretschmann) geometry with a thin Au substrate showed large changes in peak shape, peak position, and peak width in the C-H stretching region, indicating titanium penetration into the LB film and decomposition of the original well-packed monolayer structure. LB monolayers formed on a platinum oxide (PtO(x)) surface showed remarkably small changes after Ti deposition, indicating only a slight increase in disorder and no significant metal penetration into the film. Films on SiO2 substrates showed reactivity between that of Au and PtO(x). These differences in reactivity can be correlated primarily with the amount of available oxygen associated with each substrate, including surface oxide layers and water incorporated within the LB film.