Search Results (38)

This review article covers the synthesis and design of conjugated polymers for carefully adjusting energy levels and energy band gap (EBG) to achieve the desired photovoltaic performance. The formation of bonds and the delocalization of electrons over conjugated chains are both explained by the molecular orbital theory (MOT). The intrinsic characteristics that classify conjugated polymers as semiconducting materials come from the EBG of organic molecules. A quinoid mesomeric structure (D-A ↔ D⁺ = A⁻) forms across the major backbones of the polymer as a result of alternating donor–acceptor segments contributing to the pull–push driving force between neighboring units, resulting in a smaller optical EBG. Furthermore, one of the most crucial factors in achieving excellent performance of the polymer is improving the morphology of the active layer. In order to improve exciton diffusion, dissociation, and charge transport, the nanoscale morphology ensures nanometer phase separation between donor and acceptor components in the active layer. It was demonstrated that because of the exciton’s short lifetime, only small diffusion distances (10–20 nm) are needed for all photo-generated excitons to reach the interfacial region where they can separate into free charge carriers. There is a comprehensive explanation of the architecture of organic solar cells using single layer, bilayer, and bulk heterojunction (BHJ) devices. The short circuit current density (J_sc), open circuit voltage (V_oc), and fill factor (FF) all have a significant impact on the performance of organic solar cells (OSCs). Since the BHJ concept was first proposed, significant advancement and quick configuration development of these devices have been accomplished. Due to their ability to combine great optical and electronic properties with strong thermal and chemical stability, conjugated polymers are unique semiconducting materials that are used in a wide range of applications. According to the fundamental operating theories of OSCs, unlike inorganic semiconductors such as silicon solar cells, organic photovoltaic devices are unable to produce free carrier charges (holes and electrons). To overcome the Coulombic attraction and separate the excitons into free charges in the interfacial region, organic semiconductors require an additional thermodynamic driving force. From the molecular engineering of conjugated polymers, it was discovered that the most crucial obstacles to achieving the most desirable properties are the design and synthesis of conjugated polymers toward optimal p-type materials. Along with plastic solar cells (PSCs), these materials have extended to a number of different applications such as light-emitting diodes (LEDs) and field-effect transistors (FETs). Additionally, the topics of fluorene and carbazole as donor units in conjugated polymers are covered. The Stille, Suzuki, and Sonogashira coupling reactions widely used to synthesize alternating D–A copolymers are also presented. Moreover, conjugated polymers based on anthracene that can be used in solar cells are covered. Full article

A solution casting method has been utilisedto fabricate plasticisednatural gelatin (NG)-based polymer electrolyte films. The NG electrolyte with 50 wt.% glycerol and 13 wt.% sodium nitrate (NaNO₃) attained the highest ionic conductivity of 1.67 × 10⁻⁴ S cm⁻¹. Numerous techniques were used to characterisethe NG films to assess their electrochemical performance. The data obtained from impedance spectroscopy for the plasticisedsystem, such as bulk resistance (Rb), arerelatively low. Thiscomprehensive study has been focused on dielectric characteristics and electric modulus parameters. The plasticisedsystem has shown eligibility for practice in energy storage devices with electrochemical strength up to 2.85 V. The TNM data based on ion transference number (tion) and electron transference number (te) determine the identity of the main charge carrier, ion. The redox peaks in the cyclic voltammograms have not been observed as evidence of charge accumulation other than the Faradaic process at the electrode–electrolyte interface. The GCD plot reveals a triangle shape and records arelatively low drop voltage. The high average efficiency of 90% with low ESR has been achieved over 500 cycles, indicating compatibility between electrolyte and electrode. The average power density and energy density of the plasticisedare 700 W/kg and 8 Wh/kg, respectively. Full article

Pyrite ${\mathrm{FeS}}_2$ has become the focus of many researchers in thin-film photovoltaics because it has some possibilities in photovoltaics. In this manuscript, we present an experimental and a theoretical study of the electronic structure of pyrite ${\mathrm{FeS}}_2$ alloyed with a small concentration of 1.19% of ruthenium (${\mathrm{Fe}}_{0.9881}{\mathrm{Ru}}_{0.0119}{\mathrm{S}}_2$) by using the Linear Muffin-Tin Orbital Method in the Atomic-Sphere approximation (LMTO-ASA) calculations and the density of states. We observed that the bandgap of ${\mathrm{FeS}}_2$ increases from $0.90508$ to $1.21586 \mathrm{eV}$ when we replace $~1.19\%$ of the $\mathrm{Fe}$ atoms with ruthenium atoms $\left(\mathrm{x}=0.0119 \mathrm{concentration} \mathrm{of} \mathrm{Ru}\right)$. We prove that this low concentration of Ru saved the gap states and the electronic and optical properties of ${\mathrm{FeS}}_2$ pyrite. Our calculated electronic bandgap is $1.21586 \mathrm{eV}$ and direct. Our results confirm that the symmetric operation of the space ${\mathrm{T}}_{\mathrm{h}}^6 \left(\mathrm{Pa}3\right)$ saves electronic structure of iron pyrite when alloyed with ruthenium. Full article

The effect of ethynylene or ethynylene–thiophene spacers on the band gap of alternating polymers, containing 4,9-naphthothiadiazole units as an acceptor and 2,7-linked fluorene repeat units as a donor, were investigated. The Sonogashira coupling reaction was employed to prepare the two novel copolymers, namely ((9,9-dioctyl-fluorene)-2,7-diethynylene-alt-4,9-2,1,3-naphthothiadiazole (PFDENT) and poly(5,5’-(9,9-dioctyl-fluorene-2,7-diyl)bis(ethynyl-2-thienyl)-alt-4,9-(2,1,3-naphthothiadiazole) (PFDTENT). The optical, electrochemical and thermal properties of the two obtained polymers were widely investigated and compared. Both resulting polymers showed low solubility in common organic solvents and moderate molecular weights. It is believed that the introduction of acetylene linkers rather than acetylene–thiophene spacers on the polymer chains reduces the steric hindrance between the donor and acceptor units which leads to the adoption of more planar structures of polymeric chains, resulting in decreased molecular weights of the resulting conjugated polymers. Thus, both ethynylene-based polymers and ethynylene–thiophene-based polymers showed red-shifted absorption maxima compared to their counterpart (thiophene-based polymer), owing to the adoption of more planar structures. Optical studies revealed that the new ethynylene and ethynylene–thiophene-based polymers displayed low band gaps compared to their thiophene analogue polymer PFDTNT. Both resulting polymers showed good thermal stability. X-ray diffraction (XRD) patterns of both polymers revealed that PFDENT and PFDTENT possessed an amorphous nature in solid state. Full article

A facile methodology system for synthesizing solid polymer electrolytes (SPEs) based on methylcellulose, dextran, lithium perchlorate (as ionic sources), and glycerol (such as a plasticizer) (MC:Dex:LiClO₄:Glycerol) has been implemented. Fourier transform infrared spectroscopy (FTIR) and two imperative electrochemical techniques, including linear sweep voltammetry (LSV) and electrical impedance spectroscopy (EIS), were performed on the films to analyze their structural and electrical properties. The FTIR spectra verify the interactions between the electrolyte components. Following this, a further calculation was performed to determine free ions (FI) and contact ion pairs (CIP) from the deconvolution of the peak associated with the anion. It is verified that the electrolyte containing the highest amount of glycerol plasticizer (MDLG3) has shown a maximum conductivity of 1.45 × 10⁻³ S cm⁻¹. Moreover, for other transport parameters, the mobility (μ), number density (n), and diffusion coefficient (D) of ions were enhanced effectively. The transference number measurement (TNM) of electrons (t_el) was 0.024 and 0.976 corresponding to ions (t_ion). One of the prepared samples (MDLG3) had 3.0 V as the voltage stability of the electrolyte. Full article

The attention to a stable and ionic conductive electrolyte is driven by the limitations of liquid electrolytes, particularly evaporation and leakage, which restrain their widespread use for electrochemical device applications. Solid polymer electrolyte (SPE) is considered to be a potential alternative since it possesses high safety compared to its counterparts. However, it still suffers from low device efficiency due to an incomplete understanding of the mechanism of ion transport parameters. Here, we present a simple in situ solution casting method for the production of polymer-based electrolytes using abundantly available methylcellulose (MC) doped at different weight percentages of potassium thiocyanate (KSCN) salt. Fourier transform infrared (FTIR), and electrochemical impedance spectroscopy (EIS) methods were used to characterize the prepared samples. Based on EIS simulation and FTIR deconvolution associated with the SCN anion peak, various ion transport parameters were determined. The host MC medium and KSCN salt have a strong interaction, which was evident from both peak shifting and intensity alteration of FTIR spectra. From the EIS modeling, desired electric circuits correlated with ion movement and chain polarization were drawn. The highest ionic conductivity of 1.54 × 10⁻⁷ S cm⁻¹ is determined from the fitted EIS curve for the film doped with 30 wt.% of KSCN salt. From the FTIR deconvoluted peak, free ions, ions in contact with one another, and ion aggregates were separated. The extracted ion transport parameters from the EIS method and FTIR spectra of the SCN anion band confirm that both increased carrier concentration and their mobility were crucial in improving the overall conductivity of the electrolyte. The dielectric investigations were further used to understand the conductivity of the films. High dielectric constants were observed at low frequencies for all MC:KSCN systems. The dispersion with a high dielectric constant in the low-frequency band is ascribed to the dielectric polarization. The wide shift of M″ peak towards the high frequency was evidenced by the MC-based electrolyte impregnated with 30 wt.% of KSCN salt, revealing the improved ionic movement assisted with chain segmental motion. The AC conductivity pattern was influenced by salt concentration. Full article

Stable and ionic conducting electrolytes are needed to make supercapacitors more feasible, because liquid electrolytes have leakage problems and easily undergo solvent evaporation. Polymer-based electrolytes meet the criteria, yet they lack good efficiency due to limited segmental motion. Since metal complexes have crosslinking centers that can be coordinated with the polymer segments, they are regarded as an adequate method to improve the performance of the polymer-based electrolytes. To prepare plasticized proton conducting polymer composite (PPC), a simple and successful process was used. Using a solution casting process, methylcellulose and dextran were blended and impregnated with ammonium thiocyanate and zinc metal complex. A range of electrochemical techniques were used to analyze the PPC, including transference number measurement (TNM), linear sweep voltammetry (LSV), cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The ionic conductivity of the prepared system was found to be 3.59 × 10⁻³ S/cm using the EIS method. The use of glycerol plasticizer improves the transport characteristics, according to the findings. The carrier species is found to have ionic mobility of 5.77 × 10⁻⁵ cm² V⁻¹ s⁻¹ and diffusion coefficient of 1.48 × 10⁻⁶ cm² s⁻¹ for the carrier density 3.4 × 10²⁰ cm⁻³. The TNM revealed that anions and cations were the predominant carriers in electrolyte systems, with an ionic transference value of 0.972. The LSV approach demonstrated that, up to 2.05 V, the film was stable, which is sufficient for energy device applications. The prepared PPC was used to create an electrical double-layer capacitor (EDLC) device. The CV plot exhibited the absence of Faradaic peaks in the CV plot, making it practically have a rectangular form. Using the GCD experiment, the EDLC exhibited low equivalence series resistance of only 65 Ω at the first cycle. The average energy density, power density, and specific capacitance values were determined to be 15 Wh/kg, 350 W/kg, and 128 F/g, respectively. Full article

Although robotic vision systems offer a promising technology solution for rapid and reconfigurable in-process 3D inspection of complex and large parts in contemporary manufacturing, measurement accuracy poses a challenge for its wide deployment. One of the key issues in adopting a robotic vision system is to understand the extent of its measurement errors which are directly correlated with the calibration process. In this paper, a possible source of practical and inherent measurement uncertainties involved in the calibration process of a robotic vision system are discussed. The system considered in this work consists of an image sensor mounted on an industrial robot manipulator with six degrees of freedom. Based on a series of experimental tests and computer simulations, the paper gives a comprehensive performance comparison of different calibration approaches and shows the impact of measurement uncertainties on the calibration process. It has been found from the error sensitivity analysis that minor uncertainties in the calibration process can significantly affect the accuracy of the robotic vision system. Further investigations suggest that inducing errors in image calibration patterns can have an adverse effect on the hand–eye calibration process compared to the angular errors in the robot joints. Full article

In this work, the green method was used to synthesize Sn²⁺-metal complex by polyphenols (PPHs) of black tea (BT). The formation of Sn²⁺-PPHs metal complex was confirmed through UV-Vis and FTIR methods. The FTIR method shows that BT contains NH and OH functional groups, conjugated double bonds, and PPHs which are important to create the Sn²⁺-metal complexes. The synthesized Sn²⁺-PPHs metal complex was used successfully to decrease the optical energy band gap of PVA polymer. XRD method showed that the amorphous phase increased with increasing the metal complexes. The FTIR and XRD analysis show the complex formation between Sn²⁺-PPHs metal complex and PVA polymer. The enhancement in the optical properties of PVA was evidenced via UV-visible spectroscopy method. When Sn²⁺-PPHs metal complex was loaded to PVA, the refractive index and dielectric constant were improved. In addition, the absorption edge was also decreased to lower photon. The optical energy band gap decreases from 6.4 to 1.8 eV for PVAloaded with 30% (v/v) Sn²⁺-PPHs metal complex. The variations of dielectric constant versus wavelength of photon are examined to measure localized charge density (N/m*) and high frequency dielectric constant. By increasing Sn²⁺-PPHs metal complex, the N/m* are improved from 3.65 × 10⁵⁵ to 13.38 × 10⁵⁵ m⁻³ Kg⁻¹. The oscillator dispersion energy (E_d) and average oscillator energy (E_o) are measured. The electronic transition natures in composite films are determined based on the Tauc’s method, whereas close examinations of the dielectric loss parameter are also held to measure the energy band gap. Full article

In the present article, a simple technique is provided for the fabrication of a polymer electrolyte system composed of polyvinyl chloride (PVC) and doped with varying content of ammonium iodide (NH₄I) salt using solution-casting methodology. The influences of NH₄I on the structural, electrochemical, and electrical properties of PVC have been investigated using X-ray diffraction, electrochemical impedance spectroscopy (EIS), and dielectric properties. The X-ray study reveals the amorphous nature of the polymer–salt complex. The EIS measurement revealed an ionic conductivity of 5.57 × 10⁻¹⁰ S/cm for the electrolyte containing 10 wt.% of salt. Our hypothesis is provided, which demonstrated the likelihood of designing highly resistive solid electrolytes using the concept of a polymer electrolyte. Here, the results showed that the resistivity of the studied samples is not dramatically decreased with increasing NH₄I. Bode plots distinguish the decrease in resistance or impedance with increasing salt contents. Dielectric measurements revealed a decrease in the dielectric constant with the increase of NH₄I content in the PVC polymer. The relaxation time and dielectric properties of the electrolytes confirmed their non-Debye type behavior. This pattern has been validated by the existence of an incomplete semicircle in the Argand plot. Insulation materials with low ε_r have found widespread applications in electronic devices due to the reduction in delay, power dissipation, and crosstalk. In addition, an investigation of real and imaginary parts of electric modulus leads to the minimized electrode polarization being reached. Full article

This work presents the fabrication of polymer electrolyte membranes (PEMs) that are made of polyvinyl alcohol-methylcellulose (PVA-MC) doped with various amounts of ammonium iodide (NH₄I). The structural and electrical properties of the polymer blend electrolyte were performed via the acquisition of Fourier Transform Infrared (FTIR) and electrical impedance spectroscopy (EIS), respectively. The interaction among the components of the electrolyte was confirmed via the FTIR approach. Electrical impedance spectroscopy (EIS) showed that the whole conductivity of complexes of PVA-MC was increased beyond the addition of NH₄I. The application of EEC modeling on experimental data of EIS was helpful to calculate the ion transport parameters and detect the circuit elements of the films. The sample containing 40 wt.% of NH₄I salt exhibited maximum ionic conductivity (7.01 × 10⁻⁸) S cm⁻¹ at room temperature. The conductivity behaviors were further emphasized from the dielectric study. The dielectric constant, ε’ and loss, ε’’ values were recorded at high values within the low-frequency region. The peak appearance of the dielectric relaxation analysis verified the non-Debye type of relaxation mechanism was clarified via the peak appearance of the dielectric relaxation. For further confirmation, the transference number measurement (TNM) of the PVA-MC-NH₄I electrolyte was analyzed in which ions were primarily entities for the charge transfer process. The linear sweep voltammetry (LSV) shows a relatively electrochemically stable electrolyte where the voltage was swept linearly up to 1.6 V. Finally, the sample with maximum conductivity, ion dominance of t_ion and relatively wide breakdown voltage were found to be 0.88 and 1.6 V, respectively. As the ions are the majority charge carrier, this polymer electrolyte could be considered as a promising candidate to be used in electrochemical energy storage devices for example electrochemical double-layer capacitor (EDLC) device. Full article

In this report, the preparation of solid polymer electrolytes (SPEs) is performed from polyvinyl alcohol, methyl cellulose (PVA-MC), and ammonium chloride (NH₄Cl) using solution casting methodology for its use in electrical double layer capacitors (EDLCs). The characterizations of the prepared electrolyte are conducted using a variety of techniques, including Fourier transform infrared spectroscopy (FTIR), electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The interaction between the polymers and NH₄Cl salt are assured via FTIR. EIS confirms the possibility of obtaining a reasonably high conductance of the electrolyte of 1.99 × 10⁻³ S/cm at room temperature. The dielectric response technique is applied to determine the extent of the ion dissociation of the NH₄Cl in the PVA-MC-NH₄Cl systems. The appearance of a peak in the imaginary part of the modulus study recognizes the contribution of chain dynamics and ion mobility. Transference number measurement (TNM) is specified and is found to be (t_ion) = 0.933 for the uppermost conducting sample. This verifies that ions are the predominant charge carriers. From the LSV study, 1.4 V are recorded for the relatively high-conducting sample. The CV curve response is far from the rectangular shape. The maximum specific capacitance of 20.6 F/g is recorded at 10 mV/s. Full article

A solution cast technique was utilized to create a plasticized biopolymer-based electrolyte system. The system was prepared from methylcellulose (MC) polymer as the hosting material and potassium iodide (KI) salt as the ionic source. The electrolyte produced with sufficient conductivity was evaluated in an electrochemical double-layer capacitor (EDLC). Electrolyte systems’ electrical, structural, and electrochemical properties have been examined using various electrochemical and FTIR spectroscopic techniques. From the electrochemical impedance spectroscopy (EIS), a maximum ionic conductivity of 5.14 × 10⁻⁴ S cm⁻¹ for the system with 50% plasticizer was recorded. From the EEC modeling, the ion transport parameters were evaluated. The extent of interaction between the components of the prepared electrolyte was investigated using Fourier transformed infrared spectroscopy (FTIR). For the electrolyte system (MC-KI-glycerol), the t_ion and electrochemical windows were 0.964 and 2.2 V, respectively. Another electrochemical property of electrolytes is transference number measurement (TNM), in which the ion predominantly responsibility was examined in an attempt to track the transport mechanism. The non-Faradaic nature of charge storing was proved from the absence of a redox peak in the cyclic voltammetry profile (CV). Several decisive parameters have been specified, such as specific capacitance (C_s), coulombic efficiency (η), energy density (E_d), and power density (P_d) at the first cycle, which were 68 F g⁻¹, 67%, 7.88 Wh kg⁻¹, and 1360 Wh kg⁻¹, respectively. Ultimately, during the 400th cycle, the series resistance ESR varied from 70 to 310 ohms. Full article

The solution cast process is used to set up chitosan: dextran-based plasticized solid polymer electrolyte with high specific capacitance (228.62 F/g) at the 1st cycle. Fourier-transform infrared spectroscopy (FTIR) pattern revealed the interaction between polymers and electrolyte components. At ambient temperature, the highest conductive plasticized system (CDLG–3) achieves a maximum conductivity of 4.16 × 10⁻⁴ S cm⁻¹. Using both FTIR and electrical impedance spectroscopy (EIS) methods, the mobility, number density, and diffusion coefficient of ions are measured, and they are found to rise as the amount of glycerol increases. Ions are the primary charge carriers, according to transference number measurement (TNM). According to linear sweep voltammetry (LSV), the CDLG–3 system’s electrochemical stability window is 2.2 V. In the preparation of electrical double layer capacitor devices, the CDLG–3 system was used. There are no Faradaic peaks on the cyclic voltammetry (CV) curve, which is virtually rectangular. Beyond the 20th cycle, the power density, energy density, and specific capacitance values from the galvanostatic charge–discharge are practically constant at 480 W/Kg, 8 Wh/Kg, and 60 F g⁻¹, for 180 cycles. Full article

The preparation of a dextran (Dex)-hydroxyethyl cellulose (HEC) blend impregnated with ammonium bromide (NH₄Br) is done via the solution cast method. The phases due to crystalline and amorphous regions were separated and used to estimate the degree of crystallinity. The most amorphous blend was discovered to be a blend of 40 wt% Dex and 60 wt% HEC. This polymer blend serves as the channel for ions to be conducted and electrodes separator. The conductivity has been optimized at (1.47 ± 0.12) × 10⁻⁴ S cm⁻¹ with 20 wt% NH₄Br. The EIS plots were fitted with EEC circuits. The DC conductivity against 1000/T follows the Arrhenius model. The highest conducting electrolyte possesses an ionic number density and mobility of 1.58 × 10²¹ cm⁻³ and 6.27 × 10⁻⁷ V⁻¹s⁻¹ cm², respectively. The TNM and LSV investigations were carried out on the highest conducting system. A non-Faradic behavior was predicted from the CV pattern. The fabricated electrical double layer capacitor (EDLC) achieved 8000 cycles, with a specific capacitance, internal resistance, energy density, and power density of 31.7 F g⁻¹, 80 Ω, 3.18 Wh kg⁻¹, and 922.22 W kg⁻¹, respectively. Full article