Optical Absorption and Visible Photoluminescence from Thin Films of Silicon Phthalocyanine Derivatives

Investigation of Halogenated Metallic Phthalocyanine (InPcCl and F16CuPc)-Based Electrodes and Palm Substrate for Organic Solid-State Supercapacitor Fabrication

In this work, we report on the fabrication of a novel Organic Double-Layer Supercapacitor (ODLSC) using recycled palm as the substrate and electrodes based on halogenated indium and copper phthalocyanines. The electrodes were characterized using Reflectance, the Kulbeka-Munk function, and Fluorescence. Finally, their electrical behavior was evaluated, and the results were compared with those obtained for a more conventional supercapacitor fabricated on polyethylene terephthalate substrate and using indium tin oxide film for electrodes. Based on the experimental measurements of the fabricated ODLSC, the parameter identification of the classical equivalent circuit model was carried out using the Least Squares of Orthogonal Distances (LSOD) algorithm. The results indicated that the palm supercapacitor exhibited behavior more like that of traditional supercapacitors, as the root square mean error (RMSE) values in the model approximation of the experimental data were in the order of 10-7. Furthermore, the models obtained allowed a determination of the device's Electrical Impedance Spectroscopy (EIS), revealing that the Palm SC-T1 exhibited capacitive behavior. In contrast, the manufactured Palm SC-T2, PET SC-T1, and PET SC-T2 devices exhibited inductive behavior. All the materials used in this work, such as the substrates, electrodes, separator membranes, and electrolytes, have a high potential to be used in organic supercapacitors.

Cyclodextrins as nanocarriers of hydrophobic silicon phthalocyanine dichloride for the enhancement of photodynamic therapy effect

In this study, silicon phthalocyanine dichloride (SiCl2Pc) was successfully encapsulated in β-cyclodextrin (β-CD) and hydroxy-propyl-β-cyclodextrin (HP-β-CD) using the kneading method. Dynamic Light Scattering (DLS) demonstrated complexes of various hydrodynamic diameters with moderate stability in aqueous solutions. Their structural characterization by Infrared Spectroscopy (FT- IR) indicated that a part of phthalocyanine is located inside the cyclodextrin cavity. Both photophysical and photochemical studies showed that phthalocyanine's encapsulation in cyclodextrins increased its aqueous solubility. The photodynamic studies against A431 cancer cell line indicated that the complexes are more effective than pure SiCl2Pc. Pure SiCl2Pc's photodynamic effect is characterized as dose-dependent, whereas both complexes presented a biphasic dose-response photodynamic effect. For the highest energy dose of 3.24 J/cm2, pure SiCl2Pc induced mild cell toxicity. SiCl2Pc-β-CD complex was the most promising photosensitizer, exhibiting the highest photodynamic effect when irradiated at 2.16 J/cm2.

Structural determination, characterization and computational studies of doped semiconductors base silicon phthalocyanine dihydroxide and dienynoic acids

The chemical doping of silicon phthalocyanine dihydroxide (SiPc(OH)2), with (2E, 4Z)-5, 7-diphenylhepta-2, 4-dien-6-ynoic acids (DAc) with electron-withdrawing (BrDAc) and electron-donating (MeODAc) substituents is the main purpose of this work. Theoretical calculations were carried out on Gaussian16 software, with geometrical optimization of all involved species, and obtention of the highest occupied molecule orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and the respective energy gaps. The theoretical calculations show two hydrogen bridge formations: the first one as a peripheral interaction between the terminal oxygen atoms from the acid unit and hydrogen atoms from the phthalocyanine aromatic rings. The second one as the interaction at the nitrogen atoms of the phthalocyanine, which are compelled to form a new flat plane far from the original flat phthalocyanine deck. These organic semiconductors were deposited as thin films and characterized by IR spectroscopy, atomic force microscopy (AFM), and the optical parameters were gathered from UV-Vis studies. The indirect and direct optical band gap, the onset gap and the Urbach energy were obtained. In order to compare the effect of the acids as dopants of the silicon phthalocyanine, the SiPc(OH)2-DAc films were electrically characterized. The SiPc(OH)2-DAc films exhibit an ambipolar electrical behavior, which is influenced by the incidence of different lighting conditions at voltages above 0.3V. The glass/ITO/SiPc(OH)2-MeODAc/Ag reaches a maximum current of 5.68 × 10-5 A for natural light condition, while the glass/ITO/SiPc(OH)2-BrDAc/Ag, reaches a maximum current of 9.21 × 10-9 A for white illumination condition.

Influence of the Coordinated Ligand on the Optical and Electrical Properties in Titanium Phthalocyanine-Based Active Films for Photovoltaics

Tetravalent titanyl phthalocyanine (TiOPc) and titanium phthalocyanine dichloride (TiCl₂Pc) films were deposited via the high-vacuum thermal evaporation technique and subsequently structurally and morphologically characterized, to be later evaluated in terms of their optoelectronic behavior. The IR and UV-vis spectroscopy of the films displayed α- and β-phase signals in TiOPc and TiCl₂Pc. Additionally, the UV-vis spectra displayed the B and Q bands in the near-UV region of 270-390 nm and in the visible region between 600 and 880 nm, respectively. The films presented the onset gap (~1.30 eV) and the optical gap (~2.85 eV). Photoluminescence emission bands at 400-600 nm and 800-950 nm are present for the films. One-layer ITO/TiCl₂Pc or TiOPc/Ag and two-layer ITO/PEDOT:PSS/TiCl₂Pc or TiOPc/Ag planar heterojunction devices with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) deposited by the spin-coating technique were constructed. In these devices, an electrical activation energy between 0.18 and 0.21 eV and a refractive index between 1.14 and 1.44 were obtained. The devices presented a change in the J-V curves for the illuminated and darkness conditions, as much as 1.5 × 10² A/cm², related to the device architecture and phthalocyanine ligand. The latter indicates that the films should be used for optoelectronic applications.

Metal (Mn, Fe, Co, Ni, Cu, and Zn) Phthalocyanine-Immobilized Mesoporous Carbon Nitride Materials as Durable Electrode Modifiers for the Oxygen Reduction Reaction

In the search for alternative sources to replace fossil fuels, carbon nitride materials can be used in a variety of ways. In the present work, porosity is introduced to the carbon nitride material using mesoporous silica material, MCM-41, as a hard template, and a mesoporous carbon nitride (MCN) material is synthesized. Further, the MCN is modified by immobilizing metal phthalocyanine (MPc, where M = Mn, Fe, Co, Ni, Cu, and Zn). The resulting MPc-incorporated MCN materials (MPc@MCN) were tested for the electrocatalytic oxygen reduction reaction (ORR) in acidic and basic media. Detailed studies reveal that the FePc@MCN and CoPc@MCN materials exhibit higher ORR activity than the other composites in 0.1 M KOH. FePc@MCN follows a direct four-electron oxygen reduction mechanism and shows ORR onset potential (vs RHE) at 0.93 V (in 0.1 M KOH), which is very close to the onset potential exhibited by the state-of-the-art material, Pt-C (1.0 V), and higher than several similar composites of MPc with carbon supports tested in similar environments. Besides, due to the inherent property of coordination through nitrogen present on the MCN, FePc@MCN shows excellent stability even after 3000 cyclic voltammetry (CV) cycles. FePc@MCN was found to have a better methanol tolerance in comparison to Pt-C in basic medium. CoPc@MCN shows a highly selective two-electron reduction reaction in both acidic and basic media at lower overpotential than many of the reported catalysts for the two-electron oxygen reduction. Therefore, these materials (FePc@MCN and CoPc@MCN) can be used as suitable alternatives to replace Pt and other expensive materials in ORR and related applications.

Improving the uniformity of holographic recording using multi-layer photopolymer: Part II. Experimental results

In the first part of this study, a 3D nonlocal photopolymerization driven diffusion model was developed and applied to simulate the absorption and polymerization taking place during holographic exposures of a multi-layer. The Beer-Lambert law was used to choose appropriate dye concentrations for each layer, with the objective of improving the resulting volume grating uniformity and thus diffraction characteristics. The predictions made, using previously estimated physical parameter values, indicated that improvements in the uniformity of the recorded modulation were possible. In this paper the results of experiments carried out to explore the validity of these predictions are presented. Improvements in material response are demonstrated experimentally, with improved grating diffraction (narrower angular selectivity) being observed for appropriately sensitized multi-layers.

Revealing the Chemistry between Band Gap and Binding Energy for Lead-/Tin-Based Trihalide Perovskite Solar Cell Semiconductors

A relationship between reported experimental band gaps (solid) and DFT-calculated binding energies (gas) is established, for the first time, for each of the four ten-membered lead (or tin) trihalide perovskite solar cell semiconductor series examined in this study, including CH₃ NH₃ PbY₃ , CsPbY₃ , CH₃ NH₃ SnY₃ and CsSnY₃ (Y=I_(3-x) Br_x=1-3 , I_(3-x) Cl_x=1-3 , Br_(3-x) Cl _x=1-3 , and IBrCl). The relationship unequivocally provides a new dimension for the fundamental understanding of the optoelectronic features of solid-state solar cell thin films by using the 0 K gas-phase energetics of the corresponding molecular building blocks.

New Development of Membrane Base Optoelectronic Devices

It is known that one factor that affects the operation of optoelectronic devices is the effective protection of the semiconductor materials against environmental conditions. The permeation of atmospheric oxygen and water molecules into the device structure induces degradation of the electrodes and the semiconductor. As a result, in this communication we report the fabrication of semiconductor membranes consisting of Magnesium Phthalocyanine-allene (MgPc-allene) particles dispersed in Nylon 11 films. These membranes combine polymer properties with organic semiconductors properties and also provide a barrier effect for the atmospheric gas molecules. They were prepared by high vacuum evaporation and followed by thermal relaxation technique. For the characterization of the obtained membranes, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to determine the chemical and microstructural properties. UV-ViS, null ellipsometry, and visible photoluminescence (PL) at room temperature were used to characterize the optoelectronic properties. These results were compared with those obtained for the organic semiconductors: MgPc-allene thin films. Additionally, semiconductor membranes devices have been prepared, and a study of the device electronic transport properties was conducted by measuring electrical current density-voltage (J-V) characteristics by four point probes with different wavelengths. The resistance properties against different environmental molecules are enhanced, maintaining their semiconductor functionality that makes them candidates for optoelectronic applications.

A Review of Hologram Storage and Self-Written Waveguides Formation in Photopolymer Media

Photopolymer materials have received a great deal of attention because they are inexpensive, self-processing materials that are extremely versatile, offering many advantages over more traditional materials. To achieve their full potential, there is significant value in understanding the photophysical and photochemical processes taking place within such materials. This paper includes a brief review of recent attempts to more fully understand what is needed to optimize the performance of photopolymer materials for Holographic Data Storage (HDS) and Self-Written Waveguides (SWWs) applications. Specifically, we aim to discuss the evolution of our understanding of what takes place inside these materials and what happens during photopolymerization process, with the objective of further improving the performance of such materials. Starting with a review of the photosensitizer absorptivity, a dye model combining the associated electromagnetics and photochemical kinetics is presented. Thereafter, the optimization of photopolymer materials for HDS and SWWs applications is reviewed. It is clear that many promising materials are being developed for the next generation optical applications media.

Optical and Electrical Properties of TTF-MPcs (M = Cu, Zn) Interfaces for Optoelectronic Applications

Sandwich structures were fabricated by a vacuum deposition method using MPc (M = Cu, Zn), with a Tetrathiafulvalene (TTF) derivative, and Indium Tin Oxide (ITO) and aluminum electrodes. The structure and morphology of the deposited films were studied by IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The absorption spectra of TTF derivative-MPc (M = Cu, Zn) thin films deposited at room temperature were recorded in the spectral range 200-1000 nm. The optical band gap of the thin films was determined from the (αhν)(1/2) vs. hν plot. The direct-current (DC) electrical properties of the glass/ITO/TTFderiv-MPc (M = Cu, Zn)/Al structures were also investigated. Changes in conductivity of the derivative-TTF-enriched Pc compounds suggest the formation of alternative paths for carrier conduction. At low voltages, forward current density obeys an ohmic I-V relationship; at higher voltages, conduction is mostly due to a space-charge-limited conduction (SCLC) mechanism.