Zinc Phthalocyanine Thin Films Research Articles

Variation in zinc phthalocyanine molecular orientation on SrTiO3(100) surface

The molecular orientation of zinc phthalocyanine (ZnPc) thin films grown on SrTiO3(100) substrate was studied using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The results revealed that the molecular orientation changed with the deposition of ZnPc. At the deposition of 0.4 monolayer equivalent (MLE), the π* resonance at grazing incidence was more prominent than that at normal incidence, indicating a lying configuration. By comparing the experimental results with theoretical calculations, the molecular orientation angle for the ZnPc ultrathin film was estimated to be 30°. During the deposition upto 4.3 MLE, the orientation angle increased with increasing ZnPc molecular density in the layer and reached 61°, which is close to that of the α-crystalline films. The dependence of the molecular orientation on the deposition amount indicates that the molecular orientation in the ZnPc ultrathin films is governed by the ZnPc molecular density on the SrTiO3(100) substrate surface.

Mode-locked ytterbium-doped fiber laser with zinc phthalocyanine thin film saturable absorber

A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine (ZnPc) thin film as passive saturable absorber (SA) in ytterbium-doped fiber laser (YDFL). The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses. The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz. At pump power of 277 mW, the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ, respectively. ZnPc has a high chemical and photochemical stability, and its significance for use as a potential SA in a mode-locked laser is reported in this work.Graphical

Interfacial rearrangements and strain evolution in the thin film growth of ZnPc on glass

We report on the characterization of the growth of vacuum-deposited zinc phthalocyanine (ZnPc) thin films on glass through a combination of in situ grazing incidence x-ray scattering, x-ray reflectivity, and atomic force microscopy. We found that the growth at room temperature proceeds via the formation of two structurally unique substrate-induced interfacial layers, followed by the growth of the $\ensuremath{\gamma}$-ZnPc polymorph thereafter (thickness $\ensuremath{\approx}1.0$ nm). As the growth of the bulk $\ensuremath{\gamma}$-ZnPc progresses, a substantial out-of-plane lattice strain ($\ensuremath{\approx}15%$ relative to $\ensuremath{\gamma}$-ZnPc powder) is continually relaxed during the thin film growth. The rate of strain relaxation was slowed after a thickness of $\ensuremath{\approx}13$ nm, corresponding to the transition from layer growth to island growth. The findings reveal the real-time microstructural evolution of ZnPc and highlight the importance of substrate-induced strain on thin film growth.

Picosecond Soliton Pulse Generation with a Zinc Phthalocyanine Thin-Film Saturable Absorber Via Mode Locking in an Erbium-Doped Fiber Laser Cavity

Picosecond Soliton Pulse Generation with a Zinc Phthalocyanine Thin-Film Saturable Absorber Via Mode Locking in an Erbium-Doped Fiber Laser Cavity

Erratum: "Morphological and optical properties of α- and β-phase zinc (II) phthalocyanine thin films for application to organic photovoltaic cells" [J. Chem. Phys. 153, 144704 (2020)

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Sensing Behavior of Metal-Free Porphyrin and Zinc Phthalocyanine Thin Film towards Xylene-Styrene and HCl Vapors in Planar Optical Waveguide.

The sensing behavior of a thin film composed of metal-free 5, 10, 15, 20-tetrakis (p-hydroxy phenyl) porphyrin and zinc phthalocyanine complex towards m-xylene, styrene, and HCl vapors in a homemade planar optical waveguide (POWG), was studied at room temperature. The thin film was deposited on the surface of potassium ion-exchanged glass substrate, using vacuum spin-coating method, and a semiconductor laser light (532 nm) as the guiding light. Opto-chemical changes of the film exposing with hydrochloric gas, m-xylene, and styrene vapor, were analyzed firstly with UV-Vis spectroscopy. The fabricated POWG shows good correlation between gas exposure response and absorbance change within the gas concentration range 10–1500 ppm. The limit of detection calculated from the logarithmic calibration curve was proved to be 11.47, 21.08, and 14.07 ppm, for HCl gas, m-xylene, and styrene vapors, respectively. It is interesting to find that the film can be recovered to the initial state with trimethylamine vapors after m-xylene, styrene exposures as well as HCl exposure. The gas-film interaction mechanism was discussed considering protonation and π-π stacking with planar aromatic analyte molecules.

Temperature-dependent phase composition of fluorinated zinc phthalocyanine thin films and their sensing properties towards gaseous NO2

This work presents a temperature-dependent phase composition study of thin films (200 nm) of fluorinated zinc phthalocyanines (4F, 16F) and their chemiresistive response towards NO2 gas.

Passively Q-switched Ytterbium-doped fiber laser using zinc phthalocyanine thin film as saturable absorber

This paper presents a ZnPc: PVA film as saturable absorber (SA) for Q-switched pulse generation at 1-micron region. The SA film was obtained by embedding the ZnPc into polyvinyl alcohol (PVA). It was inserted into an Ytterbium-doped fiber laser (YDFL) cavity to act as a Q-switcher. The Q-switching operation was realized at the center of wavelength of 1036 nm with the minimum pulse width of 2.2 μs. The highest repetition rate and the maximum pulse energy were obtained at 63 kHz and 91 nJ, respectively. A signal to noise ratio (SNR) as high as 49 dB was observed, which indicates a stable operation of Q-switching in the YDFL cavity. This is the first demonstration of the use of ZnPc as Q-switcher in 1-micron wavelength region. A stable and high energy Q-switched pulse was realized with the proposed SA, which was obtained with a low-cost fabrication process.

Morphological and optical properties of α- and β-phase zinc (∥) phthalocyanine thin films for application to organic photovoltaic cells.

We have investigated the morphological and optical properties of α- and β-phase Zinc Phthalocyanine (ZnPc) thin films for application to organic photovoltaic cells (OPVs). It was found that the α-phase is completely converted to the β-phase by thermal annealing at 220 °C under ultrahigh vacuum conditions. When the α- to β-phase transition takes place, the surface roughness of the ZnPc film became flat uniformly with a nanometer order of unevenness by anisotropic growth of crystalline grains along a lateral direction to substrates. Correspondingly, the optical absorbance of the β-phase film became greater by 1.5-2 times than that of the α-phase one in an ultraviolet-visible-near infrared (UV-vis-NIR) wavelength range, which plays a role in increasing the number of photogenerated excitons. On the contrary, time-resolved photoluminescence measurements showed that the average lifetime of excitons for the β-phase film became shorter by 1/6-1/7 than that for the α-phase one, which plays a role in decreasing the number of excitons achieving the donor/acceptor interface where excitons are separated to carriers (holes and electrons). Both the increase in the number and the shortening in the average lifetime have a trade-off relationship with each other for contribution to the photoelectric conversion efficiency of OPVs. Then, we examined an external quantum efficiency (EQE) of OPVs using the α- and β-phase films as a donor and obtained that the former OPV (α-phase) exhibits a higher EQE by ∼2 times than the latter one (β-phase) in the wavelength range of 400 nm-800 nm.

Zinc phthalocyanine thin film as saturable absorber for Q-switched pulse generation

Abstract This paper demonstrated the use of Zinc phthalocyanine (ZnPc) thin film as saturable absorber (SA) to generate Q-switched pulse train in erbium-doped fiber laser (EDFL) cavity. The film was prepared in three methods; ZnPc was embedded into, casted onto and spin-coated onto the polyvinyl alcohol (PVA) film and the samples are referred to embedding ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA, respectively in this paper. The SA was inserted between two optical fiber ferrules in the laser cavity. The Q-switched fiber laser operates at a wavelength of 1561.4, 1560.4 and 1559.5 nm for embedding ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA SAs respectively. The pulse repetition rate increases from 25.19 to 48 kHz, 30.3 to 43 kHz, and 21.5 to 32.2 kHz as the pump power rises from 115.8 to 148 mW, 119 to 141 mW, and 109.6 to 135 mW for the SA fabrication methods of ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA, respectively. However, the pulse width decreases from 8.28 to 3.6 µs for embedding ZnPc:PVA, 10.8 to 4.9 µs for casting ZnPc/PVA, and 12.3 to 6 µs for spin-coating ZnPc/PVA. The results indicate that the ZnPc materials is feasible for use as SA in realizing a reliably stable and flexible Q-switching pulse lasers for 1.5 µm region. The maximum pulse energies are calculated to be 71, 32 and 50 nJ for the three SA fabrication methods of ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA. To the best of the authors’ knowledge, this is the first time ZnPc material is used as a SA device for a stable Q-switched laser pulse operation.

THICKNESS AND ANNEALING EFFECTS ON THE STRUCTURAL AND OPTICAL CONDUCTIVITY PARAMETERS OF ZINC PHTHALOCYANINE THIN FILMS

In this work, the effects of the thin film thicknesses on the structural, optical absorption, energy band gap, dielectric spectra and optical conductivity parameters of the Zinc phthalocyanine thin films are considered. Thin films of ZnPc of thicknesses of 50-600 nm which are coated onto glass substrates are observed to exhibit amorphous nature of growth. The polycrystalline monoclinic ZnPc phase of the films is obtained via annealing the films at 200 oC in a vacuum atmosphere. Increasing the ZnPc films thickness shrunk the energy band gap in the B- and Q- bands and decreased both of the optical conductivities and free holes density in the Q-band. The increase in the film thickness is also observed to decrease the plasmon frequency and the drift mobility of holes in the films. The highest dielectric constant is obtained for films of thicknesses of 100 nm. The annealing process enhanced the optical absorption, redshifts the energy band gap value and the critical energy of the absolute maxima of dielectric constant. In addition, while the heat treatment enhanced both of the scattering times at femtosecond level and the drift mobility, it reduced the free holes density, and the plasmon frequency.

Phase transition induced spectral tuning of dual luminescent crystalline zinc-phthalocyanine thin films and OLEDs

We analyze the impact of the first order structural phase transition between the α- and β-phases in crystalline zinc-phthalocyanine thin films on their luminescent behavior. Upon optical excitation, two intensity maxima governing the dual fluorescence can be attributed to thin film excimer emission of the α-phase at 930 nm and bulk Frenkel exciton emission of the corresponding β-phase at 780 nm. Comprehensive temperature and time dependent studies on the structural phase transition reveal a controllable shift of spectral weight between these two maxima. Applying this approach to thin film devices, we demonstrate the preparation of dual luminescent organic light emitting diodes with tunable emission characteristics in the near infrared, which are of interest as electro-optical units in future hybrid photonic devices.

Room Temperature BTX Sensor Based on Zinc Phthalocyanine Thin Film

This study deals with comparing interaction mechanisms of 2(3), 9(10), 16(17), 23(24)-Tetra-((5-bromo-2-methoxyphenyl)diazenyl) phthalocyaninatozinc(II) (zinc phthalocyanine) thin film with versatile chemical vapours: stable and electron donating aromatic vapours namely; benzene, toluene and xylene. The variation in electrical conductivity of zinc phthalocyanine is used as an indicator of the BTX- zinc phthalocyanine interactions. It was found that, unexpectedly, the exposure of the sensor surface to BTX vapors cause an increase in sensor current. It was observed for low concentrations of BTX vapours that, zinc phthalocyanine based sensor exhibits maximum and minimum sensitivities towards toluene and xylene vapors, respectively. However, the maximum and minimum sensitivities of the sensor gradually changes from xylene to benzene for high concentrations of BTX vapors. These findings was concluded in the framework of reaction activation energy and the presence of some water dissociated species, such as H+ or OH−.

Characterization and Dielectric Properties of Vacuum Deposited Zinc Phthalocyanine Thin Film

The present paper reports the structural, optical and electrical properties of zinc phthalocyanine (ZnPc) thin films which were grown by the thermal evaporation technique at different substrate temperatures of 312, 363 and 413 K and dielectric response of sandwich geometry of ZnPc thin films have also been studied within frequency range 1 Hz–50 KHz. The crystal structures of these ZnPc films have been characterized using the X-ray diffraction technique. Raman spectra and photoluminescence have been recorded to study the molecular orientations in the ZnPc films for different substrate temperatures. The absorption spectra of the ZnPc films have shown two absorption bands – namely, the Soret band and Q-band. The activation energy values of these films have been determined to be lying in the range of 0·70–0·75 eV. Hole mobility values of ZnPc films have been calculated by using differential susceptance method. The capacitance and dielectric constant have been found to decrease with increase in frequency.

Electron beam modified zinc phthalocyanine thin films for radiation dosimeter application

Present study deals with the effect of electron beam irradiation on electrical and gas sensing properties of zinc phthalocyanine (ZnPc) thin film prepared on flexible Biaxially Oriented Polyethylene Terephthalate (BOPET) sheet. The electron beam irradiation of ZnPc films were carried out using a 10MeV RF Linear accelerator, under different radiation dose levels from 1kGy to 30kGy. The pristine and irradiated films were characterized by using X-ray photoelectron spectroscopy, Atomic Force microscopy, UV–vis spectroscopy and X-ray diffraction. Samples irradiated in the dose range of 1–18kGy exhibit linear enhancement of electrical conductance due to increasing content of adsorbed oxygen. Beyond 18kGy the sample exhibit saturation in the content of adsorbed oxygen as well as in electrical conductance. The pristine ZnPc films exhibit excellent chemi-resistive response towards H2S gas in 1–20ppm range at room temperature. The response of the irradiated films decreases monotonically with increasing electron beam dose due to the strong binding of oxygen at the Zn sites. A plausible mechanism of electron beam induced modification of ZnPc films and its implication on charge transport as well as chemi-resistive gas sensing behavior are discussed. This work highlight the utilization of ZnPc thin films as potential radiation dosimeter based upon linear rise in electrical conductance.

Study of all-optical switching properties of zinc phthalocyanine thin film by pump-probe technique

The nonlinear optical absorption, refraction and switching behavior of Zinc phthalocyanine (Zn(II)Pc) thin films are reported. Z-scan technique is employed to study the nonlinear absorption and nonlinear refraction behavior of the thin films with nanosecond pulses of Nd:YAG laser at ∼532nm. Optical switching behavior of the dye is studied using pump-probe technique with ∼5ns pulses of Nd:YAG at ∼532nm as the pump beam and ∼632.8nm cw He-Ne laser as the probe beam. The switching behavior of the dye is attributed to excited state absorption (ESA) of the probe beam by the dye molecules. Probe beam modulation with increasing pump intensity is also investigated.

Synthesis and characterization of novel 4-Tetra-4-Tolylsulfonyl ZnPc thin films for optoelectronic applications

Novel 4-Tetra-4-Tolylsulfonyl:zinc phthalocyanine and simple zinc phthalocyanine were synthesized. Our materials were grown on glass substrates by spin coating technique. Thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electronic micrograph (SEM), atomic force microscopy (AFM), spectrophotometer and Hall effect measurement. X-ray spectra reveal that 4-Tetra-4-Tolylsulfonyl:zinc phthalocyanine (4T4TS:ZnPc) and zinc phthalocyanine (ZnPc) thin films have a monoclinic crystalline structure in β phase. The surface properties and chemical composition were detailed using XPS measurement. SEM were used to investigate the surface morphology for 4T4TS:ZnPc and ZnPc thin films. Atomic force microscopy images have shown a decrease in surface roughness after substitution. Optical properties were investigated by measuring transmission and reflection spectra. Electrical properties were studied and the different electrical parameters was measured and compared on glass, silicon and tin dioxide substrates by Hall Effect technique. All obtained results indicate an improvement in physical properties of 4T4TS:ZnPc which allows used it in optoelectronic applications.

Enhancement of NO2 gas detection in hybrid silver nanoparticles-phthalocyanine thin films

Phthalocyanine-functionalized plasmonic sensing systems are typically based on Kretschmann configuration. Such scheme of detection utilizes spectral or angular modulation of reflected light, which is induced by surface plasmon's excitation in the metal film on prism. Phthalocyanine's layer plays a role of analyte adsorber. In present paper we offer another approach to phthalocyanine-plasmonic sensing, where both local surface plasmon resonance and optical absorption of phthalocyanines are simultaneously detected. Hybrid Ag nanoparticles (AgNps) - low symmetrical A3B zinc phthalocyanine (ZnPc) thin films were prepared, and their NO2 gas sensitive properties were examined. Since the plasmon resonance of AgNps was properly tuned to charge-transfer band of ZnPc-NO2 complex, we found out more than two-fold increase of the optical response to NO2 exposure in AgNps-ZnPc thin films compared to ZnPc films without AgNps.

Controlled growth of ZnPc nanostructures via heat assisted solvent vapour treatment method and application in photovoltaic devices

We demonstrated a facile and well controlled way for surface nanostructuring of Zinc Phthalocyanine (ZnPc) thin films. Investigations have been carried out on the structural and optical properties of as deposited and acetone vapour treated ZnPc thin films. Furthermore, organic photovoltaic (OPV) device has been also fabricated employing plane/nanostructured-ZnPc films as electron donor and [6,6]-phenyl C61 butyric acid methyl ester as the electron acceptor layer in conventional bilayer device architectures. OPV device performance has been compared with devices with planer and nanostructured-ZnPc thin films. Three times improvement in power conversion efficiency (η %) has been observed in nanostructured-ZnPc treated for 20 s acetone treatment.

Erratum to: The properties of samarium-doped zinc oxide/phthalocyanine structure for optoelectronics prepared by pulsed laser deposition and organic molecular evaporation

Samarium-doped zinc oxide (ZnO:Sm)/zinc phthalocyanine (ZnPc) thin film multilayer structure was prepared by combination of pulsed laser deposition (PLD) and organic molecular evaporation (OME). ZnO:Sm thin film was grown by PLD (Nd:YAG, λ = 266 nm, τ = 6 ns) from Sm2O3:ZnO (1 % Sm) target in oxygen ambient at pressure of 10 and 20 Pa at room temperature on fused silica and Si(100) substrates. ZnPc thin film was deposited on ZnO:Sm layer by OME. ZnO:Sm films of c-axis-oriented hexagonal wurtzite structure and α-form ZnPc were obtained. Emission of intra-4f transition in Sm3+ ions and photoluminescence enhancement of near-band-edge emission of ZnO in ZnO:Sm/ZnPc were observed. Electrical properties were not affected by Sm3+ dopant as ZnO:Sm film exhibited high electrical resistivity ~5 × 104 Ω cm.