Search Results (60)

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article

For the first time, hybrid nanocomposites based on poly(2,5-dichloro-3,6-bis(phenylamino)-p-benzoquinone) (PCPAB) and multi-walled carbon nanotubes (MWCNTs) were obtained and the influence of the preparation method on their structure and functional properties was demonstrated. The nanocomposites were obtained both by ultrasonic mixing of PCPAB and MWCNTs, and via in situ oxidative polymerization of CPAB in the presence of MWCNTs or MWCNTs with the addition of ZnO. The formation of hybrid nanocomposites occurs due to non-covalent interaction (π-stacking) between the graphene structures of the MWCNT surface and the phenyl rings of PCPAB. It was found that during the in situ oxidative polymerization of CPAB in the presence of MWCNTs, the growth of polymer chains occurred in close proximity to the filler surface, which led to the formation of a polymer coating. ZnO particles, localized on MWCNTs, on the one hand, prevent their aggregation, and on the other hand, create additional polymerization reaction centers due to the coordination of the Zn-O bond at the H and O atoms of the monomer. An increase in the concentration of reaction centers as a result led to a 2–2.5-fold reduction in the induction polymerization period. According to SEM data, in this case, a more ordered and denser polymer layer is formed due to intermolecular complexation between the main and side chains of the growing polymer with the participation of Zn²⁺ ions formed as a result of the transformation of ZnO to ZnCl₂ in the acidic reaction medium of polymerization. The results of the study of the frequency dependences of conductivity indicate a hopping mechanism of conductivity of nanocomposites. The electrical conductivity of nanocomposites depends on their production method and the MWCNT content and varies between 0.5 and 1.1 S∙cm⁻¹, which is 6–12 times higher than the conductivity of the original polymer. Thermogravimetric analysis revealed that the nanocomposites exhibit enhanced thermal stability compared to PCPAB. The best results were shown by nanocomposites with a higher content of MWCNTs, for which the residual mass at 450 °C was 51–53%. Full article

In this study, we investigated the effect of annealing ultrathin silver (Ag) films of varying thicknesses (1–6 nm) on both their optical absorption and the performance of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) organic solar cells (OSCs). The Ag films were deposited on indium tin oxide (ITO) anodes and annealed at 300 °C for 1–2 h to modify the anodic interface. The optical and electrical properties of the resulting devices were systematically characterized and optimized. The results revealed that a 1 nm AgO layer annealed for 2 h significantly enhanced the device performance, yielding a 6% increase in power conversion efficiency compared to the standard configuration. This improvement is attributed to two main factors: (i) a 25% increase in light absorption of the AgO/P3HT:PCBM film due to localized surface plasmon resonance of Ag nanoparticles and (ii) an 11% reduction in series resistance resulting from the favorable alignment of the Ag work function with the ITO anode and the polymer HOMO, which facilitates efficient hole extraction. These findings highlight the potential of ultrathin, annealed Ag/AgO interfacial layers as an effective strategy to enhance light absorption and charge transport in OSCs. Full article

Two amide-preformed aromatic diamine monomers, N,N-bis(4-(3-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (m-6) and N,N-bis(4-(4-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (p-6), were synthesized and utilized to prepare two series of electroactive poly(amide-imide)s (PAIs) through a two-step polycondensation reaction with commercially available aromatic tetracarboxylic dianhydrides. The obtained polymers exhibited solubility in various polar organic solvents, and most of them could form transparent, flexible films via solution casting. Thermal analysis indicated glass transition temperatures (T_g) ranging from 250 °C to 277 °C, as measured by DSC, with no significant weight loss observed before 400 °C in TGA tests. Cyclic voltammograms (CV) of the polymer films on ITO-coated glass substrates revealed two reversible oxidation redox pairs between 0.67 and 1.04 V vs. Ag/AgCl in an electrolyte-containing acetonitrile solution. The PAI films showed stable redox activity with high optical contrast both in the visible and near-infrared regions, transitioning from colorless in the neutral state to green and blue in the oxidized states. Furthermore, the polymer films retained good electrochemical and electrochromic stability even after more than 100 cyclic switching operations. The PAIs displayed outstanding electrochromic performance, including high optical contrast (up to 95%), rapid response times (below 4.6 s for coloring and 5.7 s for bleaching), high coloration efficiency (up to 240 cm²/C), and low decay in optical contrast (less than 5% after 100 switching cycles for most PAIs). Full article

The increasing impact of global warming is predominantly driven by the extensive use of fossil fuels, which release significant amounts of greenhouse gases into the atmosphere. This has led to a critical need for alternative, sustainable energy sources that can mitigate environmental impacts. Photovoltaic technology has emerged as a promising solution by harnessing renewable energy from the sun, providing a clean and inexhaustible power source. Perovskite solar cells (PSCs) are a class of hybrid organic–inorganic solar cells that have recently attracted significant scientific attention due to their low cost, relatively high efficiency, low–temperature processing routes, and longer carrier lifetimes. These characteristics make them a viable alternative to traditional fossil fuels, reducing the carbon footprint and contributing to the fight against global warming. In this study, the SCAPS–1D numerical simulator was used in the computational analysis of a PSC device with the configuration FTO/ETL/BaZr(S_0.6Se_0.4)₃/HTL/Ir. Different hole transport layer (HTL) and electron transport layer (ETL) material were proposed and tested. The HTL materials included copper (I) oxide (Cu₂O), 2,2′,7,7′–Tetrakis(N,N–di–p–methoxyphenylamine)9,9′–spirobifluorene (spiro–OMETAD), and poly(3–hexylthiophene) (P₃HT), while the ETLs included cadmium suphide (CdS), zinc oxide (ZnO), and [6,6]–phenyl–C₆₁–butyric acid methyl ester (PCBM). Finally, BaZr(S_0.6Se_0.4)₃ was proposed as an absorber, and a fluorine–doped tin oxide glass substrate (FTO) was proposed as an anode. The metal back contact used was iridium. Photovoltaic parameters such as short circuit density (I_sc), open circuit voltage (V_oc), fill factor (FF), and power conversion efficiency (PCE) were used to evaluate the performance of the device. The initial simulated primary device with the configuration FTO/CdS/BaZr(S_0.6Se_0.4)₃/spiro–OMETAD/Ir gave a PCE of 5.75%. Upon testing different HTL materials, the best HTL was found to be Cu₂O, and the PCE improved to 9.91%. Thereafter, different ETLs were also inserted and tested, and the best ETL was established to be ZnO, with a PCE of 10.10%. Ultimately an optimized device with a configuration of FTO/ZnO/BaZr(S_0.6Se_0.4)₃/Cu₂O/Ir was achieved. The other photovoltaic parameters for the optimized device were as follows: FF = 31.93%, J_sc = 14.51 mA cm⁻², and V_oc = 2.18 V. The results of this study will promote the use of environmentally benign BaZr(S_0.6Se_0.4)₃–based absorber materials in PSCs for improved performance and commercialization. Full article

This study examines the impact of incorporating a thin gold (Au) nanofilm as an interfacial buffer layer between the anode and the active layer in poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM) organic solar cells. A nominal 6 nm Au layer was thermally evaporated onto indium tin oxide (ITO) substrates and subsequently annealed at 550 °C for 30 and 60 min before completing the device fabrication. The optical, morphological, and electrical consequences of introducing these annealed Au films were systematically evaluated. Optical measurements revealed a marked enhancement in light absorption: the unannealed Au/P3HT:PCBM film showed a 54% increase at 560 nm, rising to 79% after 60 min of annealing, attributed to localized surface plasmon resonance. In contrast, electrical characterization indicated a decline in overall photovoltaic performance, with all parameters decreasing except for a modest 2% increase in fill factor. Atomic force microscopy further revealed that the actual Au nanofilm thickness was approximately 16 nm—significantly higher than the nominal 6 nm—leading to increased roughness and aggregation. The excessive thickness and roughened morphology of the annealed Au film likely hindered charge transport and reduced exciton generation by scattering and reflecting incident light away from the active layer. These findings highlight the competing effects of Au nanofilms: while they enhance optical absorption, they simultaneously degrade electrical performance. This underscores the importance of carefully optimizing nanofilm thickness and morphology to achieve a balanced interplay between plasmonic enhancement and electronic transport in organic solar cells. Full article

Separators are generally considered inert components in lithium-ion batteries. In the past, some electroactive polymers have been successfully applied in separator modifications for overcharge protection or as acid scavengers. This study highlights the first use of two “electroactive” carbazole polymers (copolymer 9-phenyl-9H-carbazole-phenyl [PCP] and poly(9-vinylcarbazole) [PVC]), which were each applied separately as coatings on the cathode-facing side of commercial Celgard 2325 separators, respectively, to enhance the cycling performance of 0.3Li₂MnO₃·0.7LiMn_0.5Ni_0.5O₂//graphite (LMR-NM//Gr) full cells through interphase engineering. The team observed an irreversible polymer oxidation process of the carbazole-functionalized polymers—occurring only during the first charge—for the modified separator cells, and the results were confirmed by dQ/dV analysis, cyclic voltammetry measurements, and nuclear magnetic resonance characterizations. During this oxidation, carbazole polymers participate in the process of interphase formation, contributing to the improved cycling performance of LMR-NM//Gr batteries. Particularly, oxidation takes place at voltages of ~4.0 and ~3.5 V when PCP and PVC are used as separator coatings, which is highly irreversible. Further postmortem examinations suggest that the improvements using these modified separators arise from the formation of higher-quality and more inorganic SEI, as well as the beneficial CEI enriched in LixPOyFz. These interphases effectively inhibit the crosstalk effect by reducing TM dissolution. Full article

At present, lead halide PVSKSCs are promising photovoltaic cells but have some limitations, including their low stability in ambient conditions and the toxicity of lead. Thus, it will be of great significance to explore lead-free perovskite materials as an alternative absorber layer. In recent years, the numerical simulation of perovskite solar cells (PVSKSCs) via the solar cell capacitance simulation (SCAPS) method has attracted the attention of the scientific community. In this work, we adopted SCAPS for the theoretical study of lead (Pb)-free PVSKSCs. A cesium bismuth iodide (CsBi₃I₁₀; CBI) perovskite-like material was used as an absorber layer. The thickness of the CBI layer was optimized. In addition, different electron transport layers (ETLs), such as titanium dioxide (TiO₂), tin oxide (SnO₂), zinc oxide (ZnO), and zinc selenide (ZnSe), and different hole transport layers, such as spiro-OMeTAD (2,2,7,7-tetrakis(N,N-di(4-methoxyphenylamine)-9,9′-spirobifluorene), poly(3-hexylthiophene-2,5-diyl) (P₃HT), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), and copper oxide (Cu₂O), were explored for the simulation of CBI-based PVSKSCs. A device structure of FTO/ETL/CBI/HTL/Au was adopted for simulation studies. The simulation studies showed the improved photovoltaic performance of CBI-based PVSKSCs using spiro-OMeTAD and TiO₂ as the HTL and ETL, respectively. An acceptable PCE of 11.98% with a photocurrent density (J_sc) of 17.360258 mA/cm², a fill factor (FF) of 67.10%, and an open-circuit voltage (V_oc) of 1.0282 V were achieved under the optimized conditions. It is expected that the present study will be beneficial for researchers working towards the development of CBI-based PVSKSCs. Full article

We analyzed the interaction of three materials, reduced graphene oxide (RGO), [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), and poly(3-hexylthiphene) (P3HT), as well as the dependence of its photophysical properties within the temperature range of 90 to 300 K. The nanocomposite of the films was analyzed by optical absorption ultraviolet–visible (UV-Vis) and photoluminescence (PL) and emission ellipsometry (EE) as a function of sample temperature. The surface morphology was studied by atomic force microscopy (AFM). We noted that onset levels (E_onset) of the nanocomposite of P3HT and RGO are smaller than the others. The PL spectra showed the presence of anomalies in the emission intensities in the nanocomposite of P3HT and PCBM. It was also possible to determine the electron–phonon coupling by calculating the Huang–Rhys parameters and the temperature dependence of samples. Through EE, it was possible to analyze the degree of polarization and the anisotropy. We observed a high degree of polarized emission of the P3HT films, which varies subtly according to the temperature. For nanocomposites with RGO, the polarization degree in the emission decreases, and the roughness on the surface increases. As a result, the RGO improves the energy transfer between adjacent polymer chains at the cost of greater surface roughness. Then, the greater energy transfer may favor applications of this type of nanocomposite in organic photovoltaic cells (OPVCs) with enhancement in energy conversion efficiency. Full article

This study explores the potential of copper-doped nickel oxide (Cu:NiO) as a hole transport layer (HTL) in flexible photovoltaic (PV) devices using a combined first-principles and finite element analysis approach. Density functional theory (DFT) calculations reveal that Cu doping introduces additional states in the valence band of NiO, leading to enhanced charge transport. Notably, Cu:NiO exhibits a direct band gap (reduced from 3.04 eV in NiO to 1.65 eV in the stable supercell structure), facilitating the efficient hole transfer from the active layer. Furthermore, the Fermi level shifts towards the valence band in Cu:NiO, promoting hole mobility. This translates to an improved photovoltaic performance, with Cu:NiO-based HTLs achieving ~18% and ~9% power conversion efficiencies (PCEs) in perovskite and poly 3-hexylthiophene: 1-3-methoxycarbonyl propyl-1-phenyl 6,6 C 61 butyric acid methyl ester (P3HT:PCBM) polymer solar cells, respectively. Finally, a finite element analysis demonstrates the potential of these composite HTLs with Poly 3,4-ethylene dioxythiophene)—polystyrene sulfonate (PEDOT:PSS) in flexible electronics design and the optimization of printing processes. Overall, this work highlights Cu:NiO as a promising candidate for high-performance and flexible organic–inorganic photovoltaic cells. Full article

With the continuous advancement of industrial technology, higher demands have been placed on the properties of gear oils, such as oxidation stability and shear resistance. Herein, the oxidation stability of high-viscosity metallocene poly-$\alpha$-olefins (mPAOs) was improved by chemical modification via aromatic amine alkylation. The modified mPAO base oils were synthesized separately with diphenylamine (mPAO-DPA) and N-phenyl-$\alpha$-naphthylamine (mPAO-NPA), and their applicability in industrial gear oil formulations was evaluated. The composition and physicochemical properties of the obtained samples were assessed using ¹H NMR spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, and the American Society for Testing and Materials standards (ASTM D445, ASTM D2270, ASTM D92, etc.) confirming the successful completion of the alkylation reaction. The oxidation stability of the samples was also evaluated using pressurized differential scanning calorimetry. The initial oxidation temperature of mPAO-NPA (230 °C) was 53 °C higher than that of mPAO, and the oxidation induction period of mPAO-DPA was nearly twice that of mPAO-NPA. Thermogravimetric analysis in air revealed the increased thermal decomposition temperature and improved thermal stability of modified mPAO. ISO VG 320 industrial gear oils were formulated using mPAO alkylated with N-phenyl-$\alpha$-naphthylamine(Lub-2) and commercially purchased PAO100 (Lub-1) as base oil components. The antioxidant performance of two industrial gear oils was evaluated through oven oxidation and rotating oxygen bomb tests. The oxidation induction period of Lub-2 was 30% higher than that of Lub-1, with the latter having a lower acid number and a smaller increase in viscosity at 40 °C. Finally, the friction performance of the samples was assessed on a four-ball friction tester, revealing the synergistic effect of the mPAO-NPA base oil with the HiTEC 3339 additive, forming a more stable oil film with a smaller wear scar diameter. Full article

The photoelectrochemical cells (PECs) performing high-efficiency conversions of solar energy into both electricity and high value-added chemicals are highly desirable but rather challenging. Herein, we demonstrate that a PEC using the oxidatively electropolymerized film of a heteroleptic Ru(II) complex of [Ru(bpy)(L)₂](PF₆)₂ Ru1 {bpy and L stand for 2,2′-bipyridine and 1-phenyl-2-(4-vinylphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline respectively}, polyRu1, as a working electrode performed both efficient in situ synthesis of hydrogen peroxide and photocurrent generation/switching. Specifically, when biased at −0.4 V vs. saturated calomel electrode and illuminated with 100 mW·cm⁻² white light, the PEC showed a significant cathodic photocurrent density of 9.64 μA·cm⁻². Furthermore, an increase in the concentrations of quinhydrone in the electrolyte solution enabled the photocurrent polarity to switch from cathodic to anodic, and the anodic photocurrent density reached as high as 11.4 μA·cm⁻². Interestingly, in this single-compartment PEC, the hydrogen peroxide yield reached 2.63 μmol·cm⁻² in the neutral electrolyte solution. This study will serve as a guide for the design of high-efficiency metal-complex-based molecular systems performing photoelectric conversion/switching and photoelectrochemical oxygen reduction to hydrogen peroxide. Full article

The widespread use of hydrophilic intraocular lenses (IOLs) in eye surgery, fabricated by poly-2-(hydroxyethyl methacrylate) (PHEMA), has highlighted their calcification as a serious problem, implying that their surgical explantation is a rather risky process. The field of biomaterials has been developing rapidly in recent years, with research interest turning to the development of novel materials which involve either copolymers of PHEMA or protective functional coatings. Graphene coatings are particularly attractive because of their respective unique properties. In the present work, we present the results of the investigation of the development of graphene coatings on hydrophilic IOLs and their subsequent performance with respect to calcification opacification. Hydrophilic IOLs with a water content of 18% by weight were coated with graphene oxide (GO) by equilibration with GO suspensions in water. The concentrations of the suspensions ranged from 1 × 10⁻⁴ to 20 × 10⁻⁴% w/v. The GO suspensions were equilibrated with the IOLs for 5 days at a constant temperature, 37 °C, and rotated in 30 mL tubes end over end. This treatment resulted in the formation of a uniform coating of GO on the IOLs verified by scanning electron microscopy (SEM) and other physicochemical methods. The contact angle of the GO-coated IOLs decreased significantly in comparison with the uncoated IOLs. The GO-coated IOLs exhibited a higher tendency to calcify in supersaturated solutions simulating aqueous humor (SAH). The growth rate of hydroxyapatite (Ca₅(PO₄)₃OH, HAP) on GO-coated IOLs was higher in comparison with the respective untreated IOLs. The conversion of the GO coating via a reduction with phenyl hydrazine resulted in the formation of a reduced-graphene (rGO) surface film, as identified by Raman and XPS spectroscopy. The rGO film was hydrophobic (contact angle 100°) and did not calcify in supersaturated calcium phosphate solutions. Full article

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted considerable attention due to the excellent optoelectronic properties of perovskite materials. The energy consumption and high cost issues of metal electrode evaporation should be addressed before large-scale manufacturing and application. We developed an effective metal electrode evaporation procedure for the fabrication of high-efficiency planar heterojunction (PHJ) PSCs, with an inverted device structure of glass/indium tin oxide (ITO)/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA)/perovskite/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/(E)-β-caryophyllene (BCP)/Ag. The effect of the evaporation rate for an evaporator with a small-volume metal cavity on the performance of PHJ-PSC devices was investigated systematically. Through controlling the processes of Ag electrode evaporation, the charge dynamics of the devices were studied by analyzing their charge recombination resistance and lifetime, as well as their defect state density. Our findings reveal that the evaporation rate of an evaporator with a small cavity is favorable for the performance of PHJ-PSCs. As a result, PHJ-PSCs fabricated using a very thin, non-doped PTAA film exhibit photoelectric conversion efficiency (PCE) of 19.21%, with an open-circuit voltage (Voc) of 1.132 V. This work showcases the great potential of rapidly evaporating metal electrodes to reduce fabrication costs, which can help to improve the competitiveness in the process of industrialization. Full article

Reduced graphene oxide (RGO) has been extensively studied and applied in optoelectronic systems, but its unstable dispersion in organic solvents has limited its application. To overcome this problem, the newly designed and developed aggregation-induced emission (AIE) material poly[(9,9-bis(6-azidohexyl)-9H-fluorene)-alt-(9-(4-(1,2,2-triphenylvinyl)phenyl)-9H-carbazole)] (PAFTC) was covalently grafted onto RGO to produce (PFTC-g-RGO). The solubility of two-dimensional graphene was improved by incorporating it into the backbone of PAFTC to form new functional materials. In resistive random access memory (RRAM) devices, PFTC-g-RGO was used as the active layer material after it was characterized. The fabricated Al/PFTC-g-RGO/ITO device exhibited nonvolatile bistable resistive switching performances with a long retention time of over 10⁴ s, excellent endurance of over 200 switching cycles, and an impressively low turn-ON voltage. This study provides important insights into the future development of AIE polymer-functionalized nanomaterials for information storage. Full article