Poly 3-octylthiophene Research Articles

Advancing Multi-Ion Sensing with Poly-Octylthiophene: 3D-Printed Milker-Implantable Microfluidic Device.

On-site rapid multi-ion sensing accelerates early identification of environmental pollution, water quality, and disease biomarkers in both livestock and humans. This study introduces a pocket-sized 3D-printed sensor, manufactured using additive manufacturing, specifically designed for detecting iron (Fe2+), nitrate (NO3 -), calcium (Ca2+), and phosphate (HPO4 2-). A unique feature of this device is its utilization of a universal ion-to-electron transducing layer made from highly redox-active poly-octylthiophene (POT), enabling an all-solid-state electrode tailored to each ion of interest. Manufactured with an extrusion-based 3D printer, the device features a periodic pattern of lateral layers (width = 80µm), including surface wrinkles. The superhydrophobic nature of the POT prevents the accumulation of nonspecific ions at the interface between the gold and POT layers, ensuring exceptional sensor selectivity. Lithography-free, 3D-printed sensors achieve sensitivity down to 1ppm of target ions in under a minute due to their 3D-wrinkled surface geometry. Integrated seamlessly with a microfluidic system for sample temperature stabilization, the printed sensor resides within a robust, pocket-sized 3D-printed device. This innovation integrates with milking parlors for real-time calcium detection, addressing diagnostic challenges in on-site livestock health monitoring, and has the capability to monitor water quality, soil nutrients, and human diseases.

The Determination of the Electronic Parameters of Thin Amorphous Organic Films by Ellipsometric and Spectrophotometric Study

The aim of this work was the determination of the basic optical parameters and electronic structure of conjugated polymer films by two commonly used techniques—spectrophotometry and ellipsometry. Poly(3-hexylthiophene (P3HT) and poly(3-octylthiophene (P3OT) conductive polymers films deposited on a glass substrate by the spin-coating technique showed very comparable surface structures composed of grains of similar sizes and shapes. X-ray tests confirmed that the polythiophene layers are amorphous, which confirmed the correctness of the choice of the optical models used. Selected optical models (Lorentz, Tauc–Lorentz and Cody–Lorentz) have been applied in order to determine the thickness, and optical parameters such as refractive index and extinction coefficient, absolute absorption and electronic parameters (energy gap Eg, amplitude A and broadening B). Spectral absorption determined from spectrophotometric measurement is similar to the absorption spectrum obtained from the ellipsometry method with the application of oscillator models.

Screen-printed Microsensors Using Polyoctyl-thiophene (POT) Conducting Polymer As Solid Transducer for Ultratrace Determination of Azides.

Two novel all-solid-state potentiometric sensors for the determination of azide ion are prepared and described here for the first time. The sensors are based on the use of iron II-phthalocyanine (Fe-PC) neutral carrier complex and nitron-azide ion-pair complex (Nit-N3−) as active recognition selective receptors, tetradodecylammonium tetrakis(4-chlorophenyl) borate (ETH 500) as lipophilic cationic additives and poly(octylthiophene) (POT) as the solid contact material on carbon screen-printed devices made from a ceramic substrate. The solid-contact material (POT) is placed on a carbon substrate (2 mm diameter) by drop-casting, followed, after drying, by coating with a plasticized PVC membrane containing the recognition sensing complexes. Over the pH range 6-9, the sensors display fast (< 10 s), linear potentiometric response for 1.0 × 10−2–1.0 × 10−7 M azide with low detection limit of 1.0 × 10−7 and 7.7 × 10−8 M (i.e., 6.2–4.8 ng/ml) for Fe-PC/POT/and Nit-N3−/POT based sensors, respectively. The high potential stability and sensitivity of the proposed sensors are confirmed by electrochemical impedance spectroscopy (EIS) and constant-current chronopotentiometry measurement techniques. Strong membrane adhesion and absence of delamination of the membrane, due to possible formation of a water film between the recognition membranes and the electron conductor are also verified. The proposed sensors are successfully applied for azide quantification in synthetic primer mixture samples. Advantages offered by these sensors are the robustness, ease of fabrication, simple operation, stable potential response, high selectivity, good sensitivity and low cost.

Thermo-optical properties of conducted polythiophene polymer films used in electroluminescent devices

In this paper we present results of ellipsometric studies of thin organic poly-3hexylthiophene–(P3HT) and poly-3octylthiophene (P3OT) films performed in temperature range 20–300 °C. The optical dispersion spectra of refractive and extinction indices of presented organic films was determined in wavelength range 190–1700 nm for temperatures within in a given range. Also thermo-ellipsometric investigations allowed to find temperature dependence on film thickness. The determination of thermal changes of thickness and refractive index allowed us to calculate thermo-optical coefficients (TOC) for P3HT and P3OT layers for many wavelengths in measured spectral range. The obtained values of thermo-optical coefficients of thin P3HT layers, determined from combined ellipsometric and spectro-photometric investigations, are negative in visible part of spectral range of the order of 10−4 [1/K] .

Ionophore-Based Voltammetric Ion Activity Sensing with Thin Layer Membranes.

As shown in recent work, thin layer ion-selective multi-ionophore membranes can be interrogated by cyclic voltammetry to detect the ion activity of multiple species simultaneously and selectively. Additional fundamental evidence is put forward on ion discrimination with thin multi-ionophore-based membranes with thicknesses of 200 ± 25 nm and backside contacted with poly-3-octylthiophene (POT). An anodic potential scan partially oxidizes the POT film (to POT(+)), thereby initiating the release of hydrophilic cations from the membrane phase to the sample solution at a characteristic potential. Varying concentration of added cation-exchanger demonstrates that it limits the ion transfer charge and not the deposited POT film. Voltammograms with multiple peaks are observed with each associated with the transfer of one type of ion (lithium, potassium, and sodium). Experimental conditions (thickness and composition of the membrane and concentration of the sample) are chosen that allow one to describe the system by a thermodynamic rather than kinetic model. As a consequence, apparent stability constants for sodium, potassium, and lithium (assuming 1:1 stoichiometry) with their respective ionophores are calculated and agree well with the values obtained by the potentiometric sandwich membrane technique. As an analytical application, a membrane containing three ionophores was used to determine lithium, sodium, and potassium in artificial samples at the same location and within a single voltammetric scan. Lithium and potassium were also determined in undiluted human plasma in the therapeutic concentration range.

HYBRID ORGANIC SOLAR CELLS BLENDED WITH CNTs

In this paper, composite carbon nanotubes (C-CNTs); single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are synthesized using an ultrasonic nebulizer in a large quartz tube for photovoltaic device fabrication in poly-3-octyl-thiophene (P3OT)/ n - Si heterojunction solar cells. We found that the device fabricated with C-CNTs shows much better photovoltaic performance than that of a device without C-CNTs. The device with C-CNTs shows open-circuit voltage (Voc) of 0.454 V, a short circuit current density (Jsc) of 12.792 mA/cm2, fill factor (FF) of 0.361 and power conversion efficiency of 2.098 %. Here, we proposed that SWCNTs and MWCNTs provide efficient percolation paths for both electron and hole transportation to opposite electrodes and leading to the suppression of charge carrier recombination, thereby increasing the photovoltaic device performance.

Thin Layer Ionophore-Based Membrane for Multianalyte Ion Activity Detection.

A concept is introduced that allows one to detect the activity of multiple ions simultaneously and selectively with a single ion-selective membrane. This is demonstrated with ∼300 nm thin plasticized PVC membranes containing up to two ionophores in addition to a lipophilic cation-exchanger, overlaid on an electropolymerized poly-3-octylthiophene (POT) film as the electron to ion transducer. The ion-selective membranes are formulated under ionophore depleted conditions (avoiding excess of ionophore over ion-exchanger), which is purposely different from common practice with ion-selective electrodes. Cyclic voltammetry is used to interrogate the films. An anodic scan partially oxidizes the POT underlayer, which results in the expulsion of cations from the membrane at an appropriate potential. During the scan of a membrane containing multiple ionophores, the least bound ion is expelled first, giving distinct Gaussian peak shaped ion transfer voltammetric waves that are analyzed in terms of their peak potential. These potentials are found to change with the logarithm of the ion activity, in complete analogy to ion-selective electrodes, and multiple such waves are observed with multiple ionophores that exhibit no obvious interference from the other ionophores present in the membrane. The concept is established with lithium and calcium ionophores and accompanied by a response model that assumes complete equilibration of the membrane at every applied potential. On the basis of the model, diffusion coefficients in the membrane or aqueous phase bear no influence on the peak potentials as long as thin layer behavior is observed, further confirming the analogy to a potentiometric experiment. Idealized ion transfer waves are narrower than experimental findings, which is explained by a broader than expected anodic peak for the oxidation of conducting polymer. The correspondence between experiment and theory is otherwise excellent in terms of thin layer behavior and Nernstian shift of the peaks with analyte concentration.

Impedance Analysis of CdSe Quantum Dot-Sensitized TiO2 Solar Cells Decorated with Au Nanoparticles and P3OT

Electrochemical impedance spectroscopy was used to analyze 10 μm thickness TiO2 films containing 250 nm TiO2 nanoparticles (NPs) with anatase crystalline phase deposited on FTO substrates. The TiO2 films were sensitized with CdSe quantum dots (QDs) (4.5 nm) and decorated with Au nanoparticles (NPs) (7 nm) and poly-3-octylthiophene (P3OT) in three different configurations, namely TiO2/QDs, TiO2/Au/QDs, and TiO2/Au/QDs/P3OT. The characteristic absorption bands for each component, TiO2, P3OT, CdSe QDs, and Au NPs, are centered at 338 nm (3.67 eV), 459 nm (2.7 eV), 552 nm (2.24 eV), and 517 nm (2.40 eV), respectively. The UV-Vis spectrum of the composite film TiO2/Au/QDs/P3OT shows clear absorption peaks from 338 to 700 nm. Equivalent circuits were proposed for the different configuration interfaces to fit experimental impedances. The results suggest that the introduction of Au NPs into the TiO2/Au/QDs films strongly reduces resistance to the electron flux from QDs to TiO2 and increases the overall charge transport. Meanwhile, P3OT in the TiO2/Au/QD/P3OT films promotes hole transport and increases the capacitance with the electrolyte, reducing the electron leakage and improving the fill-factor and the final light energy conversion efficiency.

Kelvin probe microscopy and current images of the degradation process of layered poly-3-octyl-thiophene structures

The changes in morphology and electronic properties of Poly-3-octyl-thiophene (P3OT) thin films produced by UV/ozone exposure have been studied using Scanning Force Microscopy techniques. The layered structures associated to crystalline P3OT domains on the polymer film show a better resilience to the degradation than the amorphous polymer background. In addition, the effect of the UV irradiation and ozone exposure on the electronic properties (contact potential, capacitance and conductivity) of the thin films is studied, finding that the degradation process of the electronic properties of these crystalline structures is different to those of the amorphous polymer background.

Molecular structure of poly(3-alkyl-thiophenes) investigated by calorimetry and grazing incidence X-ray scattering

A study of the molecular structure of regio-regular bulk poly-3-octyl-thiophene (P3OT) and poly-3-hexyl-thiophene (P3HT) and the phase transitions during heating and cooling scans in a temperature range of –158–773 °C has been performed by means of calorimetry of bulk samples and grazing incidence X-ray diffraction from synchrotron radiation. Additional calorimetric measurements were performed on samples in toluene solution. From the calorimetric temperature diagrams at different scan rates, we obtain the melting and crystallization temperatures, and we identify a low temperature calorimetric glass transition. This transition is expected because of the coexistence of amorphous and crystalline phases, which is further supported by scanning force microscopy images where lamellar structures have been observed. Thin films of both polymers have also been studied by grazing incidence X-ray diffraction, and the evolution of the (1 0 0) crystalline peak monitored as a function of sample temperature, showing different behavior in both polymers, d-spacing increases in P3HT and decreases in P3OT for increasing temperatures. The information presented in this article will be useful to design fabrication techniques for organic-based electronic devices, which could include high and low temperature cycles combined with structural quenching procedures.

Photogenerated charge carrier recombination processes in CdS/P3OT solar cells: effect of structural and optoelectronic properties of CdS films

Research and development activities in organic solar cells have been intensified in the last two decades, and the reported energy conversion efficiency in small cell samples is rapidly increased. However, the relation between cell performance and material preparation conditions is not fully understood. In this work charge carrier recombination processes in hybrid poly-3-octylthiophene (P3OT)/cadmium sulfide (CdS) photovoltaic cells were analyzed as a function of structural and optoelectronic properties of chemical bath deposited CdS thin films. The temperature of the bath solution varied between 60 and 80 °C, and the deposition time from 1 to 3 h. Charge carrier recombination times in CdS films were measured with photoconductance decay technique, whereas the same time in P3OT films was estimated by Time-of-Flight method. Charge carrier recombination rates at CdS/P3OT interface were determined by transient photovoltage technique. It is found that CdS films grown at lower solution temperature (60 °C) give a higher charge carrier recombination rate at CdS/P3OT interface and larger short-circuit current density and energy conversion efficiency values in the corresponding solar cells, in comparison with the 80 °C deposited ones. This improvement could come from the reduction of charge carrier trap density inside grains as well as at grain boundaries in lower temperature deposited CdS films.

Optoelectronic properties of chemically deposited Bi2S3 thin films and the photovoltaic performance of Bi2S3/P3OT solar cells

Thin films of bismuth sulfide (Bi2S3), prepared on conductive tin-doped indium oxide (ITO)-glass substrates by chemical deposition showed a variation of optical band gap with thickness: 1.8eV for a 50nm film (deposited at 40°C for 30min) to 1.5eV for a 200nm film deposited for 2h. The electronegativity for Bi2S3 compound is 5.3eV, as estimated from the ionization energy and electron affinity of elemental Bi and S, and thus the electron affinity of chemically deposited Bi2S3 film was deduced to be 4.5eV. In the energy level analysis of ITO/Bi2S3/P3OT/Au structure, Bi2S3 was established as an electron acceptor. To produce ITO/Bi2S3/P3OT/Au solar cell structures, poly3-octylthiophene (P3OT), prepared in the laboratory was dissolved in toluene and was drop-cast on the Bi2S3 film and a gold film was thermally evaporated. Under 100 mW/cm2 tungsten-halogen irradiation incident from the ITO-side, the cell using a Bi2S3 film with thickness of 50nm has the highest open circuit voltage (Voc) of 440mV and short-circuit current density (Jsc) of 0.022mA/cm2. The addition of a CdS thin film (90nm) between ITO and B2S3 would increase Voc to 480mV, and Jsc to 0.035mA/cm2. The role of surface morphology and optoelectronic properties of the Bi2S3 film in the photovoltaic performance of the junction is discussed.

Measurement of charge carrier recombination rates in planar hybrid CdS/poly3-octylthiophene solar cells

Hybrid bilayer solar cells have been prepared by chemical bath deposition of cadmium sulfide (CdS) thin films on conductive glass and drop cast poly3-octylthiophene (P3OT) solution on top of CdS free surface. Gold contact on P3OT film was thermally evaporated. Transient photoconductance decay method was implemented to determine the charge carrier recombination times in CdS films. The same parameter in P3OT films was estimated by time-of-flight technique. Charge recombination processes in CdS/P3OT interface were studied by transient photovoltage method. The relation between the photovoltaic performance of hybrid cells and charge recombination times at CdS/P3OT interface was analyzed as a function of P3OT film thickness. It is suggested that the ambient oxygen or humidity may originate the increased charge recombination center density in thinner P3OT films and, as a result, deteriorate the short-circuit current density and open-circuit voltage values of the corresponding hybrid cells.

Influence of UV radiation and ozone exposure on the electro-optical properties and nanoscale structure of P3OT films

The modification of the nanoscale morphology and electronic behavior as well as the mesoscopic optical properties of thin films of poly-3-octyl-thiophene (P3OT) has been studied as these films are irradiated by ultraviolet light (UV). Films of about 100 nm thickness were prepared by spin-casting a P3OT solution in toluene on glass substrates. The samples were characterized by non-contact scanning force microscopy (NC-SFM), and by optical transmission measurements for every cycle of UV irradiation. Our experimental technique allows us to perform a nanoscale study of precisely the same area of the sample in order to correlate the effect of UV irradiation to specific morphological variations rather than to variations of the statistical properties of the sample. In addition, the decrease of film thickness is measured and correlated to the observed variation of optical absorption.

The influence of UV radiation and ozone exposure on the electronic properties of poly-3-octyl-thiophene thin films

The modification of the conductivity as well as the nanoscale morphology and electrostatic properties of poly-3-octyl-thiophene (P3OT) thin films have been studied as these films are irradiated by ultraviolet light (UV). Films of about 100 nm thickness were prepared by spin-coating a P3OT solution in toluene on glass substrates. The samples were characterized by electronic transport measurements and non-contact scanning force microscopy (NC-SFM) for every cycle of UV radiation. Nanoscale topographic and electrostatic characterization using NC-SFM were performed on the same location using a specially designed sample holder. A two stage degradation process has been observed, the first one presents a chemical modification of the polymer (decoloration of sample) and free carrier mobility reduction, the second one is characterized by a strong structural modification, thickness reduction, oxygen doping and further mobility reduction. The comparison of these results on P3OT with other studies performed on P3HT will allow for a detailed analysis of the role of side-chains in the degradation mechanism upon UV irradiation.

Influence of poly3-octylthiophene (P3OT) film thickness and preparation method on photovoltaic performance of hybrid ITO/CdS/P3OT/Au solar cells

Chemically synthesized poly3-octylthiophene (P3OT) solution was spin-coated (SC) or drop-cast (DC) on cadmium sulfide thin film to form a hybrid junction of transparent conductive glass (indium-tin oxide (ITO))/CdS/P3OT/Au. XRD patterns of DC P3OT films show a couple of peaks at 2 θ between 8° and 13°. It suggests that a long-range order may exist in the slowly dried DC P3OT films. Optical absorption coefficient spectra of P3OT films exhibit the presence of polaron bands in P3OT films with thickness lower than 700 nm, which indicates that thin P3OT films are susceptible to oxygen doping. The microscopically more ordered DC P3OT films show a coplanar photoconductivity, which was absent in the SC P3OT ones. The effect of P3OT film preparation method and ambient conditions was also notable on the photovoltaic performance of CdS/P3OT-based solar cells. The potential barrier of the CdS/P3OT heterojunctions decreased as the P3OT film thickness reduced from 671 to 106 nm, which was related to the diffusion of oxygen into the polymer film. As the P3OT film thickness increased to more than 1000 nm, the open-circuit voltage ( V OC ) reached to around 1 V, close to the value suggested by fitting the current–voltage curves with the Schottky barrier diode model. But at the same time, the short-circuit current density ( J SC ) of the same cells is lowered due to the increasing charge recombination effect inside the polymer material. The simple and economic drop-cast preparation method is promising for polymer film deposition in hybrid solar cell fabrication.

Photovoltaic devices based on electrochemical–chemical deposited CdS and poly3-octylthiophene thin films

Cadmium sulfide (CdS) is a well-known wide bandgap semiconductor for solar cell applications. In this work we report an electrochemical/chemical method to prepare CdS thin films on gold (Au)-coated glass substrates. 10 nm thick of titanium (Ti) film was first sputtered on glass surface to improve the adhesion between the subsequent sputtered Au film and the glass surface. Cadmium films were then electrochemically deposited on Au surface in an acidic solution with negative potential, and the obtained glass/Ti/Au/Cd samples were annealed in H 2S atmosphere to convert Cd into CdS. XRD pattern of H 2S-annealed Cd samples shows a hexagonal wurtzite phase in CdS with (0 0 2) as the preferential crystalline plane. Photovoltaic properties were clearly shown in hybrid heterojunctions of CdS and poly3-octylthiophene (P3OT) with Au as the top and the back metal contacts.

Single Molecule Spectroscopy of Poly 3-octyl-thiophene (P3OT)

We report on the spectroscopy of isolated chains of P3OT, in a highly dilute solution in the inert polymer host poly(methyl-methacrylate) (PMMA). This environment permits a detailed analysis of emission transitions in the 1.9-2.2 eV range by suppressing the formation of the lowest emitting-energy aggregated form of P3OT. Herein it is observed that the 1.9-2.2 eV band is in fact split into low (red) and high (blue) energy forms in a highly analogous situation to that found for the conjugated polymer MEH-PPV. Another focus of this work is an investigation of the interaction of singlet and triplet excitons in P3OT. The results indicate that, like in MEH-PPV, triplet excitons are highly efficient fluorescence quenchers for P3OT, strongly quenching the fluorescence of P3OT under even relatively low excitation intensities.

Analysis of electrical parameters in heterojunctions based on poly 3-octylthiophene and cadmium sulfide thin films

Planar hybrid heterojunctions were built with poly 3-octylthiophene (P3OT) and chemical bath-deposited cadmium sulfide (CdS) thin films on a conductive glass substrate. The organic material, P3OT, acts as a light absorber and the inorganic one, CdS, as the electron acceptor. Two types of CdS films had been used: one is as-deposited and the other doped with HgCl 2 . Heterojunctions were formed by casting a chemically synthesized P3OT solution onto CdS films. The P3OT film thickness was also varied for heterojunction studies. Current vs. potential ( I – V ) characterizations under dark and illumination conditions were performed for the P3OT/CdS heterojunctions under 88 mW/cm 2 irradiance level, which show photovoltaic effect with different open circuit voltage ( V OC ) levels, being as high as 1 V for some devices. A parametric analysis of I – V curves details the effect of CdS resistivity and P3OT film thickness on series and shunt resistance of the heterojunctions.

Optical and morphological properties of chemically synthesized poly3-octylthiophene thin films

Poly3-octylthiophene (P3OT) was synthesized by direct oxidation of 3-octylthiophene using FeCl 3 as oxidant/catalyst. It was observed that the purity of FeCl 3 affected the molecular weight and polydisparity as well as the degree of regioregularity of the polymer, measured by size exclusion chromatography and by 1H nuclear magnetic resonance, respectively. Optical absorption properties of the P3OT films were analyzed as a function of solution concentration, the type of the substrates and the mole percentage of the doping agent. Morphology study with atomic force microscopy indicates that the surface roughness and the cluster size of the polymeric films are influenced by the P3OT solution concentration and the percentage molarity of ferric chloride. FeCl 3 doped P3OT films show enlarged clusters compared with the pristine one due to the introduction of FeCl 3 molecules in the original P3OT chains, a phenomenon observed in electrochemically doped heterocyclic conducting polymers reported in the literature.