Hybrid composite material based on polythiophene derivative nanofibers modified with gold nanoparticles for optoelectronics applications

Conjugated polymers have been extensively applied as active materials in nanostructured platforms for optical and electrical devices. The incorporation of metal nanoparticles (NPs) into the polymer-based platform arises as a strategy to develop novel hybrid functional nanocomposites with enhanced electrical and optical properties. However, efficient and simple processing routes to produce such nanocomposites are still on demand. In this work, we present an effective route to obtain functional nanocomposites based on electrospun nanofibers coated with gold nanoparticles, displaying interesting optical and electrical properties. Polymethyl methacrylate (PMMA) electrospun nanofibers doped with poly(3-hexyl thiophene-2,5-diyl) (P3HT) were obtained by the electrospinning technique, and displayed a strong red emission centered at 650 nm assigned to P3HT. Such nanofibers were deposited on to fluorine-doped tin oxide electrodes and with modified with gold nanoparticles (AuNPs) in order to produce hybrid composite materials. The performance of electrodes modified with PMMA/P3HT-AuNPs composite material was evaluated by impedance spectroscopy and revealed an enhancement of electron transfer kinetics, which indicates it as a potential platform for optical and electrochemical (bio)sensors.     

ZnO and conjugated polymer bulk heterojunction solar cells containing ZnO nanorod photoanode

Hybrid solar cells based on poly(3-hexylthiophene) (P3HT) and ZnO nanoparticle bulk heterojunctions (BHJ) combined with ZnO nanorod arrays were fabricated and analyzed. The dispersion of ZnO nanoparticles in P3HT is assisted by dye molecules, which function as a surface modifier for ZnO nanoparticles to improve compatibility between ZnO nanoparticles and P3HT. Compared to the ZnO nanorod/P3HT devices, the optimized cells with the ZnO nanoparticles dispersed in P3HT can significantly increase the short-circuit current and the overall power conversion efficiency from 1.36 mA cm(-2) to 2.51 mA cm(-2) and from 0.18% to 0.45% with 625 nm long ZnO nanorod arrays, respectively. The novel scheme of using the light-absorbing dye molecules both as light absorber and as surfactant for ZnO nanoparticles presents a facile route towards forming bulk heterojunction hybrid solar cells based on semiconducting nanomaterials and conjugated polymers.     

All-conjugated amphiphilic diblock copolymers for improving morphology and thermal stability of polymer/nanocrystals hybrid solar cells

Herein, the ability to optimize the morphology and photovoltaic performance of poly(3-hexylthiophene) (P3HT)/ZnO hybrid bulk-heterojunction solar cells via introducing all-conjugated amphiphilic P3HT-based block copolymer (BCP), poly(3-hexylthiophene)-block-poly(3-triethylene glycol-thiophene) (P3HT-b-P3TEGT), as polymeric additives is demonstrated. The results show that the addition of P3HT-b-P3TEGT additives can effectively improve the compatibility between P3HT and ZnO nanocrystals, increase the crystalline and ordered packing of P3HT chains, and form optimized hybrid nanomorphology with stable and intimate hybrid interface. The improvement is ascribed to the P3HT-b-P3TEGT at the P3HT/ZnO interface that has strong coordination interactions between the TEG side chains and the polar surface of ZnO nanoparticles. All of these are favor of the efficient exciton dissociation, charge separation and transport, thereby, contributing to the improvement of the efficiency and thermal stability of solar cells. These observations indicate that introducing all-conjugated amphiphilic BCP additives can be a promising and effective protocol for high-performance hybrid solar cells.     

Preparation of hydrophobic organic-silicanano composites

In this paper, we use silica nanoparticles modified by methacryloxy propyl trimethoxylsilane (KH570) as the core material, and employ polymers including hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and acrylic ester as the shell materials to prepare the hydrophobic inorganic–organic hybrid nanocomposites with a seed emulsion polymerization strategy. The size, morphologyandproperties of the core-shell structured nanoparticles are investigated by TEM and SEM. The results showthat the polymer nanocomposite has three concentric layers with silica nanoparticles in the center, acrylic polymer as the internal shell and fluorosilicone polymer as the outmost shell. By controlling the ratio of the silica nanoparticles and monomers, we can achieve each composite particle has the core-shell structure with silica nanoparticles as the core and the thin layer of fluorosilicone polymer as the shell. Compared with the traditional polymer film, the nanocomposite film shows a hydrophobic property with a contact angle of up to 100 degree. Therefore, it is feasible to prepare hydrophobic organic–inorganic nanocomposites using the method proposed here.     

Green synthesis of zinc oxide nanoparticles using tomato (Lycopersicon esculentum) extract and its photovoltaic application

With an increasing awareness of green and clean energy, zinc oxide-based solar cells were found to be suitable candidates for cost-effective and environmentally friendly energy conversion devices. In this paper, we have reported the green synthesis of zinc oxide nanoparticles (ZnONPs) by thermal method and under microwave irradiation using the aqueous extract of tomatoes as non-toxic and ecofriendly reducing material. The synthesised ZnONPs were characterised by UV–visible spectroscopy (UV–vis), infra-red spectroscopy, particle size analyser, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction study (XRD). A series of ZnO nanocomposites with titanium dioxide nanoparticles (TiO₂) and graphene oxide (GO) were prepared for photovoltaic application. Structural and morphological studies of these nanocomposites were carried out using UV–vis, SEM, XRD and AFM. The current–voltage measurements of the nanocomposites demonstrated enhanced power conversion efficiency of 6.18% in case of ZnO/GO/ TiO₂ nanocomposite.     

Surface modification of ZnO nanorods with CdS quantum dots for application in inverted organic solar cells: effect of deposition duration

Incorporating cadmium sulfide quantum dots (CdS QDs) onto ZnO nanorod (ZNRs) has been investigated to be an efficient approach to enhance the photovoltaic performance of the inverted organic solar cell (IOSC) devices based on ZNRs/poly (3-hexylthiophene) (P3HT). To synthesize CdS/ZNRs, different durations of deposition per cycle from 1 to 9 min were used to deposit CdS via SILAR technique onto ZNRs surface grown via hydrothermal method at low temperature on FTO substrate. In typical procedures, P3HT as donor polymer were spun-coating onto CdS/ZNRs to fabricate IOSC devices, followed by Ag deposition as anode by magnetron sputtering technique. Incorporation of CdS QDs has modified the morphological, structural, and optical properties of ZNRs. Incorporation of CdS QDs onto ZNRs also led to higher open circuit voltage (V_oc) and short circuit current density (J_sc) of optimum ZNRs/CdS QDs devices due to the increased interfacial area between ZNRs and P3HT for more efficient exciton dissociation, reduced interfacial charge carrier recombination as a result of lower number of oxygen defects which act as electron traps in ZnO and prolonged carrier recombination lifetime. Therefore, the ZNRs/CdS QDs/P3HT device exhibited threefold higher PCE (0.55%) at 5 min in comparison to pristine ZNR constructed device (0.16%). Overall, our study highlights the potential of ZNRs/CdS QDs to be excellent electron acceptors for high efficiency hybrid optoelectronic devices.     

The influence of the organic/inorganic interface on the organic-inorganic hybrid solar cells

Organic-inorganic hybrid solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) hybridized with ZnO nanorods were fabricated by growing vertical ZnO nanorods on indium tin oxide (ITO) substrates and filling with bulk heterojunction polymers (P3HT:PCBM). The interface between the organic and inorganic nanostructures influences the performance of the organic-inorganic hybrid solar cells. In this paper, the influence of the state of the P3HT:PCBM/ZnO interface on the performance of organic-inorganic hybrid solar cells is examined. The solar cell performance was high when the P3HT:PCBM/ZnO junction area was large. The charge separation is effective when the active layer/electron transport layer junction area is large, resulting in increasing photocurrent and a high conversion efficiency. The bulk-heterojunction polymer concentration was kept low to infiltrate into the ZnO nanorods, resulting in a large active layer/electron transport layer junction area.     

High quality ZnO/CuO nanocomposites synthesized by microwave assisted reaction

Highly crystalline zinc oxide (ZnO) and ZnO/CuO nanocomposite powders have been synthesized by a facile microwave irradiation method. The resulting powders were characterized in terms of structural, optical and morphological properties by X-ray diffraction (XRD), room temperature photoluminescence (PL) spectroscopy and scanning electron microscopy (SEM), respectively. XRD patterns revealed the formation of ZnO/CuO nanocomposites with good crystalline quality. SEM images displayed the formation of hexagonal ZnO and flower shaped agglomeration of ZnO/CuO nano-flakes with uniform production. The strong UV emission peak observed at around 380 nm show enhanced intensity for ZnO/CuO nanocomposite. Compared to ZnO nanoparticles, ZnO/CuO composites exhibit good transparency with sharp absorbance edges. The simplicity of synthesis route coupled with better optical and PL emission properties propose the microwave synthesized ZnO/CuO nanocomposite powders a promising material for optoelectronic devices.     

Quantum dot sensitized solar cell based on poly (3-hexyl thiophene)/CdSe nanocomposites

The optoelectronic properties of P3HT–CdSe nanocomposites prepared by insitu chemical oxidative polymerization were studied. CdSe QDs were synthesized by hot injection method using tri octyl phosphine oxide (TOPO) as capping ligand whereas the P3HT polymer was prepared by chemical oxidative polymerization. FTIR studies confirmed the regioregularity of the P3HT and revealed the chemical interaction of P3HT and CdSe in nanocomposite. Absorption studies showed blue shift for the nanocomposites as compare to pristine P3HT, the electron transfer from conducting polymer to the CdSe was detected by the measurements of quenching of photoluminescence from conducting polymer after the addition of semiconductor nano crystals which confirmed that an optimum amount of nanoparticles provide networking in hybrid composites. The optimal result for device prepared by P3HT–CdSe nanocomposites was open circuit voltage (V_oc) 0.5, short circuit current density (J_sc) 0.66, Fill factor (FF) 0.6855 and efficiency (η) 0.22%.     

Enhanced the structure and optical properties for ZnO/PVP nanofibers fabricated via electrospinning technique

Zinc oxide/polyvinylpyrrolidone (ZnO/PVP) nanocomposite fibers with enhanced structural, morphological and optical properties were purposefully tailored using electrospinning technique. Meanwhile, ZnO nanoparticles (NPs),with particle size of ~50 nm, were synthesized using a co-precipitation method. The nanocomposite fibers were prepared by an electrospun solution of PVP containing ZnO NPs of 2, 4, 6 and 8 wt%. Evidently, the morphological, thermal and optical properties of the ZnO/PVP nanocomposite fibers were enhanced by dispersing ZnO NPs into PVP fibers. Typically, controlling the ZnO NPs content and their dispersibility (0–8 wt%) into PVP fibers result in improved the thermal stability (an increase of onset decomposition temperature by ~120 °C above pure PVP fibers) as well as the UV–Vis protection (reduction in UV transmission by 70%) and the photoluminescence properties (a sharp UV emission around 380 nm) Overall, based on the enhanced properties, the PVP/ZnO nanocomposite fibers can be considered a promise material in optoelectronic sensors and UV photoconductor.     

Approach to a block polymer precursor from poly(3-hexylthiophene) nitroxide-mediated in situ polymerization for stabilization of poly(3-hexylthiophene)/ZnO hybrid solar cells

A cross-linked block copolymer poly(3-hexylthiophene)-b-poly(zinc dimethacrylate) (P3HT-b-PZn(MA)₂), which acted as precursor for the preparation of poly(3-hexylthiophene)/ZnO (P3HT/ZnO) hybrid film by in-situ hydrolysis, was rationally designed and synthesized via nitroxide-mediated in-situ polymerization of zinc methacrylate (Zn(MA)₂) using poly(3-hexylthiophene) alkoxyamine (P3HT-TIPNO) as macroinitiator for the purpose of stabilizing the P3HT/ZnO hybrid solar cells. The cross-linking was confirmed by the insolubility of the film in organic solvents and Fourier-transform infrared experiment. With the function of the cross-linked template, the diffusion of ZnO nanoparticles prepared by in-situ hydrolysis could be lowered to suppress the formation of large aggregations, which favored the formation of a better and more stable interpenetrating network and provided more heterojunction interfaces for exciton dissociation. As a result, the inverted device based on cross-linked P3HT/ZnO hybrid film obtained by in situ hydrolyzing P3HT-b-PZn(MA)₂ block copolymer yielded a power conversion efficiency of 0.45% under AM 1.5G illumination from a calibrated solar simulator with an intensity of 100 mW/cm², and the deterioration of the photoconversion performance was suppressed in the hybrid solar cells with the cross-linked P3HT/ZnO compared to cells with non-cross-linked P3HT/ZnO obtained by in situ hydrolyzing P3HT-TIPNO/Zn(MA)₂ blend film.     

Photovoltaic characterization of hybrid solar cells using surface modified TiO(2) nanoparticles and poly(3-hexyl)thiophene

We report on the photovoltaic performance of bulk heterojunction solar cells using novel nanoparticles of 6-palmitate ascorbic acid surface modified TiO(2) as an electron acceptor embedded into the donor poly(3-hexyl)thiophene (P3HT) matrix. Devices were fabricated by using P3HT with varying amounts of red TiO(2) nanoparticles (1:1, 1:2, 1:3?w-w ratio). The devices were characterized by measuring current-voltage characteristics under simulated AM 1.5 conditions. Incident photon to current efficiency (IPCE) was spectrally resolved. The nanoscale morphology of such organic/inorganic hybrid blends was also investigated using atomic force microscopy (AFM).     

Improved performance of ZnO thin film solar cells by doping magnesium ions

This study investigates the effect of magnesium doping on the performance of nanocrystalline zinc oxide (ZnO) thin film solar cells. Mg_xZn_1?xO (x = 0.00, 0.05, 0.075 and 0.1 %) nanoparticles were prepared by simple precipitation method. The crystallinity and morphology of the photo-anode was characterized by X-ray diffraction analysis and scanning electron microscopy. The effect of various concentrations of magnesium ions on the structural and optical properties of ZnO nanoparticles was examined. Doping of magnesium ions helps the ZnO nanoparticles to grow larger in size with rod like surface morphologies. Solar cell with 0.075 % magnesium doped ZnO electrode exhibits an enhanced short-circuit current density of 3.36 mA/cm², open-circuit photo voltage of 0.79 V, fill factor of 0.73, and overall power conversion efficiency of 2.1 %.     

Mechanisms of DC conduction in smart PMN–PT/paint nanocomposite films

Understanding conduction mechanisms in dielectric films are critical to their successful applications in devices. DC conduction mechanisms in lead magnesium niobate–lead titanate (0.67Pb (Mg_1/3Nb_2/3)O₃–0.33PbTiO₃)/Paint nanocomposite (PMN–PT/Paint) films are presented and discussed. The conventional cost-effective paint brushing technique was utilized to fabricate PMN–PT/paint nanocomposite films on copper substrate. Atomic force microscopy (AFM) has been recognized as one of the most powerful techniques for the analysis of surface morphologies because it creates 3D images at angstrom and nano scale. It has been exhaustively utilized in the analysis of dispersion of nano-metric components in nanocomposites and polymer blends. Thus, AFM analysis is applied in the present work for the surface morphological and dispersion of nanoparticles investigations in paint-based nanocomposites at different loading of PMN–PT nanoparticles. It is found that the PMN–PT nanoparticles are dispersed uniformly inside the paint matrix. The spatial distribution of PMN–PT in PMN–PT/Paint films is denser with higher PMN–PT content sample. A metal–insulator–metal capacitor was fabricated and the leakage current across was measured with varying voltage and temperature. The governing conduction mechanisms were examined and depicted. The activation energy of nanocomposite films fabricated with 2.5 and 8.98 wt% PMN–PT nanoparticles in the paint mixture are found to be 1.08 and 1.24 eV, respectively. The DC activation energy for former was found to be slightly lower then later and follow the Arrhenius relationship. Thus, showing the conduction was electronic and thermally activated.     

Preparation and characterization of ZnO/ZnS core/shell nanocomposites through a simple chemical method

In this paper, we reported the preparation of ZnO/ZnS core/shell nanocomposites by sulfidation of ZnO nanostructures via a simple hydrothermal method. The precursors of bare ZnO nanoparticles and ZnO nanorods were synthesized by a surfactant-assisted hydrothermal growth. The structural, morphological, and element compositional analysis of bare ZnO nanostructures and ZnO/ZnS core/shell nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy techniques. The XRD results indicated that the phase of bare ZnO nanoparticles and ZnO nanorods was wurtzite structure, and the phase of coated ZnS nanoparticles on the surface of bare ZnO nanostructures was sphalerite structure with the size of about 8 nm. Photoluminescence measurement was carried out, and the PL spectra of ZnO/ZnS core/shell nanocomposites revealed an enhanced UV emission and a passivated orange emission compared to that of bare ZnO nanostructures. In addition, the growth mechanism of ZnO/ZnS core/shell nanostructures through hydrothermal method was preliminarily discussed.     

Hybrid nanostructure heterojunction solar cells fabricated using vertically aligned ZnO nanotubes grown on reduced graphene oxide

Using reduced graphene oxide (rGO) films as the transparent conductive coating, inorganic/organic hybrid nanostructure heterojunction photovoltaic devices have been fabricated through hydrothermal synthesis of vertically aligned ZnO nanorods (ZnO-NRs) and nanotubes (ZnO-NTs) on rGO films followed by the spin casting of a poly(3-hexylthiophene) (P3HT) film. The data show that larger interfacial area in ZnO-NT/P3HT composites improves the exciton dissociation and the higher electrode conductance of rGO films helps the power output. This study offers an alternative to manufacturing nanostructure heterojunction solar cells at low temperatures using potentially low cost materials.     

PPy/α-Fe2O3 hybrid nanocomposites: effect of CSA doping on structural, morphological, optical and electrical transport properties

Hybrid nanocomposites of camphor sulfonic acid (CSA) doped organic polypyrrole and inorganic alpha-ferric oxide (PPy/α-Fe₂O₃) have been successfully prepared using different weight percentages of CSA (10–50 %) dispersed in PPy/α-Fe₂O₃ hybrid nanocomposite by solid state synthesis method. These hybrid nanocomposites are characterized by using various techniques such as X-ray diffraction (XRD), fourier transform infra red (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–visible spectroscopy and two probe techniques respectively. The XRD spectra revealed that the addition of CSA has no effect on crystallinity of PPy/α-Fe₂O₃ hybrid nanocomposite. The FTIR results show that, the characteristic peaks of PPy/α-Fe₂O₃ hybrid nanocomposite shift to higher wave number after addition of CSA in the PPy/α-Fe₂O₃ nanocomposites indicates some chemical interactions and better conjugation between CSA and PPy/α-Fe₂O₃ hybrid nanocomposites. SEM studies revealed that strong effect on morphology of PPy/α-Fe₂O₃ nanocomposite. The AFM analysis show uniform nano porous granular morphology. UV–visible spectroscopy studies have provided insight into the electronic interaction between the PPy, α-Fe₂O₃ and CSA. DC electrical conductivity showed a steeply increase in electrical conductivity of PPy/α-Fe₂O₃ nanocomposites with increase in amount of CSA from 10 to 50 %.     

Charging and discharging mechanisms of organic bistable devices based on ZnO nanoparticles capped with a poly N-vinylcarbazole polymer

Scanning electron microscopy and energy-dispersive spectrometer images of hybrid nanocomposites of ZnO nanoparticles capped with a poly N-vinylcarbazole (PVK) that was fabricated using the spin-coating technique showed that the ZnO nanoparticles were capped with a PVK polymer layer. The measurement of the current-voltage (I-V) of the Al/ZnO nanoparticles capped with a PVK layer/indium-tin-oxide/glass devices at 300 K showed electrical bistability and negative differential resistance, which indicate the nonvolatile nature of the memory effect of the electron captured in the ZnO nanoparticles. The charging and discharging mechanisms of the organic bistable devices that were fabricated using hybrid nanocomposites of ZnO nanoparticles capped with a PVK layer are described based on the I-V results.     

Band alignment at organic-inorganic heterojunctions between P3HT and n-type 6H-SiC

The exact band alignment at organic/inorganic semiconductor heterojunctions is influenced by a variety of properties and is difficult to predict. For organic/inorganic bilayer heterojunctions made of poly(3-hexylthiophene) (P3HT) and n-type 6H-SiC, the band alignment is determined via current-voltage measurements. For this purpose, a model equivalent circuit, combining thermionic emission and space-charge-limited current effects, is proposed which describes the behavior of the heterojunction very well. From the fitting parameters, an interface barrier height of 1.1 eV between the lowest unoccupied molecular orbital (LUMO) of P3HT and the conduction band (CB) of 6H-SiC is determined. In addition, from the maximum open circuit voltage of 6H-SiC/P3HT diodes, a difference of 0.9 eV between the highest occupied molecular orbital (HOMO) of P3HT and the CB of 6H-SiC is deduced. These two values determine the alignment of the energy bands of 6H-SiC relative to the HOMO and LUMO of P3HT. The 6H-SiC/P3HT bilayer heterojunction exhibits an open circuit voltage of ~0.5 V at room temperature, which makes such a materials system a potential candidate for bulk heterojunction hybrid solar cells with 6H-SiC nanoparticles.     

Enhanced dielectric properties and energy storage density of surface engineered BCZT/PVDF-HFP nanodielectrics

Polymer nanocomposites have proved to be promising energy storage devices for modern power electronic systems. In this work we have studied the dielectric properties and dielectric energy storage densities of 0–3 type BCZT/PVDF-HFP polymer nanocomposites with different filler volume concentrations. BCZT nanopowder was synthesized by solgel method through citrate precursor method. The structural and morphological features of the BCZT nanopowder were examined by X-ray diffraction and transmission electron microscopy. For better polymer ceramic interface coupling, BCZT was surface functionalized with extended aromatic ligand, naphthyl phosphate (NPh). The surface functionalization was validated and quantified by thermogravimetric analysis and X-ray photoelectron spectroscopy. The dielectric constant of surface passivated BCZT nanoparticles was estimated to be ~?155 using slurry technique, while the dielectric permittivity of pristine BCZT nanopowder could not be assessed due to high innate surface conductivity. BCZT/PVDF-HFP polymer nanocomposite thin films were fabricated using solution casting technique. The dispersion quality of the ceramic fillers in the polymer matrix was examined by scanning electron microscopy. Due to better polymer ceramic interface, At 5 vol% filler concentration, NPh modified nanoBCZT/PVDF-HFP films showed enhanced dielectric breakdown strength and energy storage density than untreated nanoBCZT/PVDF-HFP and even pure polymer films. Maximum energy storage density of 8.5 J cm^?3 was obtained at an optimum filler concentration of 10 vol% for surface functionalized BCZT/PVDF-HFP composite films of 10 μm thickness.