Novel donor–acceptor‐type polymers, PTBPEQ and PDPEQ, are synthesized and shown to be neutral‐state green polymeric materials with excellent transmissive oxidized states. Exceptional long‐term ...stability even after 5000 cycles, ease of electrochemical synthesis, and extremely fast switching times make these polymers paramount choices for the green component of polymer electrochromic display applications.
The current–voltage (
I
-
V
) and capacitance–voltage (
C
-
V
) characteristics of the organic heterojunction diode were investigated in a wide temperature range from 80 to 320 K and frequency range ...from 10 kHz to 1 MHz, respectively. Alternative to the copolymer partner poly(3-hexylthiophene) (P3HT) to 6,6-phenyl-C61-butyric acid methyl ester (PCBM), poly((9,9-dioctylfluorene)-2,7-diyl-(4,7-bis(thien-2-yl)2-dodecyl-benzo1,2,3triazole)) (named as copolymer in this work) was adapted to the bulk-heterojunction layer in the organic diode. Together with the use of Lif/Al bilayer electrode, the diode was fabricated as in the form of Al/LiF/copolymer:PCBM/PEDOT:PSS/ITO/glass. Under the applied bias voltage, this organic-based diode shows two-orders of magnitude rectifying behavior. According to thermionic emission (TE) model, the diode parameters such as saturation current, barrier height and ideality factor were determined and parasitic resistances were also extracted from the conventional ohmic relation. As to the temperature dependency of the diode parameters and their response to the temperature variation, barrier inhomogeneity, surface state and series resistance effects were found in dominant behavior on the current flow. The conduction mechanism was modeled by assuming low-barrier patches around the main barrier that supports TE at low temperatures and their distribution was expressed by a Gaussian function. In addition, series resistance values were detailed depending on temperature using Cheung’s model.
C
-
V
analysis was performed to evaluate the distribution of surface states at the interface as a function of frequency. Based on the
C
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V
plots, the effects of charges at these traps were observed especially at low frequencies. Additionally, from these results, Fermi level, surface potential and donor concentration values were evaluated in a wide frequency range.
Abstract
Al:LiF/PTQBT:PCBM/PEDOT:PSS/ITO/glass organic-based diode is fabricated with different weight ratios in PTQBT:PCBM active layer. The diodes D1, D2 and D3 are prepared using the precursor ...solution for spin coating process as 1:2, 1:3 and 1:4, respectively. Under dark, main diode parameters are extracted by conventional thermionic emission theory using the results of
I
−
V
measurements. Parasitic resistance contribution, non-ideal barrier height formation and high values of ideality factor indicate possible effects of space charge limited current flow mechanism on forward biased
I
−
V
characteristics. At saturated voltage region, series resistances are calculated and the results are evaluated according to Cheung’s method. The possible voltage sharing between interface layer and depletion region are also investigated by analysis of density of interface states. In addition, field effect is found in a major role on the reverse current flow and the mechanism is evaluated according to Schottky-Richardson model.
The forward and reversed biased current–voltage behaviors of the organic diode were detailed in a wide range of temperatures. In this diode, a donor–acceptor-conjugated copolymer system was ...constructed with poly((9,9-dioctylfluorene)-2,7-diyl-(2-dodecyl-benzo1,2,3triazole)) as a partner of 6,6-phenyl-C61-butyric acid methyl ester (PCBM). Two-order of magnitude rectification ratio was achieved, and the temperature-dependent values of saturation current, zero-bias barrier height, and ideality factor were extracted according to the thermionic emission model. The temperature responses of these diode parameters showed an existence of inhomogeneity in the barrier height formation. As a result, the observed non-ideal behavior was explained by Gaussian distribution of barrier height where low-barrier regions are effective in the forward biased conduction mechanism at low temperatures. Together with this analysis, series resistances were evaluated using Cheung’s functions and also density of interface states were investigated. On the other hand, reverse biased current flow was found under the dominant effect of Poole–Frenkel effects associated with these interfacial traps. The reverse current conduction mechanism was detailed by calculating characteristic field-lowering coefficients and barrier height values in the emission process from the trapped state in the range of temperatures of interest.
Donor-acceptor (DA) type monomers namely 2,5-di(thiophen-2-yl)thiazolo5,4-dthiazole (TTzTh) and 2,5-bis(3- methylthiophen-2-yl)thiazolo5,4-dthiazole (TTzMTh) were synthesized and their ...electrochemical and optoelectronic properties were investigated in detail. The spectro-electrochemical analysis showed that the alkyl chain substitution results in a shiftin the onset of the π-π· transition towards longer wavelengths. Depending on the donor substituents, the polymers exhibited optical band gaps 1.65 and 1.85 eV for PTTzThand PTTzMTh, respectively. Electrochromic studies revealed that both polymers are p-dopable and multichromic. Moreover, polymer of TTzTh(PTTzTh) has been used for the development of a glucose biosensor. Glucose oxidase (GOx) was anchored on a graphite electrode which was previously modified with a film of the conjugated polymer, PTTzThby electropolymerization. Such a sensor showed a wide linear range (0.05-2.0 mM), good sensitivity (36.32 µA/(mM·cm2) and low limit of detection (LOD) (0.075 mM) under formerly optimized conditions. Moreover, the accuracy of the biosensor was successfully tested using two different beverages to detect glucose. Electrochemical characterizations of the polymers and their biosensor application were investigated for the first time in this work.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Electrochromic supercapacitors may alert the user on the remaining capacity of the devices. The color change indicating the remaining capacity can be simply and rapidly recognized by the human eye or ...by optical instruments. A rapid indication of charged state may extend device service life and prevent overcharging, which would otherwise result in electrode aging and decomposition. In this study, a blue to the transmissive electrochromic polymer, poly(4,7‐bis(2,3‐dihydrothieno3, 4‐B1, 4dioxin‐5‐YI)‐2‐(2‐octyldodecyl)‐2H‐benzoD1, 2,3triazole) (P1C), was used in nanocomposite form with transparent silver nanowire (Ag NW) network current collectors for the fabrication of electrochromic supercapacitor electrodes. Highly conductive and transparent Ag NW networks have an important role in the realization of electrochromic supercapacitors using P1C. Fabricated Ag NW/P1C nanocomposite electrodes had a specific capacitance of 65.0 F g−1 at a current density of 0.1 A g−1. Nanocomposite electrode showed excellent stability (capacity retention of>98 %) after 11000 cycles associated with a resistance decrease associated with charge transfer.
A new monomer (DTAT) was synthesized via linking 3,4-ethylenedioxythiophene (EDOT) on anthracene. The polymer, P(DTAT) was electrosynthesized by anodic oxidation of the corresponding monomer in 0.1
M ...LiClO
4 acetonitrile (ACN) solution. The optical properties, the absorption spectra and the kinetics, were examined. Spectroelectrochemical analysis showed that P(DTAT) has an electronic band gap (due to π–π* transition) of 1.57
eV at 776
nm.
Copolymers of DTAT with EDOT were prepared in ACN/LiClO
4 (0.1
M) solvent–electrolyte couple by varying applied potential. The incorporation of an EDOT into the full conjugated backbone, DTAT, affects its optical behavior resulting in different colors; a claret red neutral state, gray and red intermediate states and a blue oxidized state.
A novel electrochemical redox process for the manipulation of adhesion of polybenzoxazine thermosets on metal surfaces is reported. The method pertains to the electrochemically driven ...hydroquinone-quinone redox couple. Several antraquinone based bisbenzoxazines possessing phenyl, benzyl and methyl furfuryl substituents were synthesized and characterized. The antraquinone bisbenzoxazines were shown to readily undergo thermally activated ring-opening polymerization in the absence of a catalyst forming cross-linked networks on metal surfaces. The substituent effect on thermal curing behaviour and thermal stability of the cured polymers were investigated. The strong binding affinities of phenolic hydroxyl groups of the anthraquinone moiety in the cured polymers promote adhesion on the metal surface. Electrochemical oxidation converts hydroquinone groups into quinone moieties resulting in the dismantling of the coated films. The generality of this electrochemical method is demonstrated by initial results on platinum electrodes as well as steel plates.
In this study three different organic semiconductors were used in the fabrication of ITO/PEDOT:PSS/Polymer:PCBM/LiF/Al configuration. Reverse current density–voltage (Jr–V) measurements of the ...samples were investigated to define the reverse-bias leakage current mechanisms on benzotriazole and benzothiadiazole based organic devices. Our results indicate that the Jr–V plot behaviors are given by linear dependence between In ( Jr) and V1/2, where Jr is the reverse current density, and V is the applied voltage. This behavior is well known as the Poole–Frenkel (PF) effect where it is found to be dominating in the reverse-bias leakage current.
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