Styrene Sulfonate Research Articles

Ultra-conductive and transparent epidermal electrodes for simultaneous dual-mode assessment of brain function

In brain science, neural activity inevitably leads to the fluctuation of cerebral blood flow. Toward comprehensively understanding brain, it is necessary to develop an epidermal electrode that can concurrently monitor the brain’s electrical activity and hemodynamic activity. Here, we report an ultra-conductive and transparent epidermal electrode for simultaneous dual-mode assessment of brain function. The electrode can accurately and imperceivably detect electrophysiological signals and functional near-infrared spectroscopy (fNIRS) optical signals. It is fabricated by two monolayer graphene with confined poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in between, namely GPG. Its extremely low sheet resistance (20.8 Ω/sq, 3727 S/cm, 129 nm) and high transmittance (∼80%) can be attributed to the more ordered alignment and dense packing of PEDOT due to the nano-confinement effect of bi-layer graphene. The strong π-π interaction between graphene and PEDOT:PSS results in the decreased stacking distance between PEDOT. Leveraging the excellent electrical property and ultrathin nature, this epidermal electrode is able to achieve low skin-electrode impedance and monitor various electrophysiological signals accurately and stably, even if the participant is in motion. Beneficial from the appropriate transparency, it can simultaneously record very weak EEG electrical signals and fNIRS optical signals, enabling dual-model brain activity analysis with high temporal and spatial resolution.

Room-ambient operation of integrated and visualized photothermoelectric system with patterned Mo2C/PEDOT: PSS flexible devices

Photothermoelectric (PTE) devices have emerged as highly promising technological advancements in energy harvesting and electronics. However, the development of PTE devices faces challenges in achieving exceptional performance, adaptable flexibility, durable stability, and compatibility within a system. This study proposes a self-powered PTE device that operates at room temperature by integrating molybdenum carbide (Mo2C)/ Poly(3,4-ethylene-dioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS) nanomaterials with a flexible poly (ethylene terephthalate) (PET) substrate. We achieve precise control over the device size through a spray coating technique and employ a laser-involved mask technique for efficient fabrication. Our Mo2C/PEDOT: PSS devices demonstrate remarkable long-term stability and outstanding flexibility and can be folded and twisted without increasing performance degradation. The devices exhibit a responsivity of 4.2 V W−1 and a detectivity of 1.2 × 108 cm Hz1/2 W−1 at 973 K black-body radiation. By employing these advantages, we integrate two potential systems—the motion tracking system and the non-destructive (NDT) imaging system—that showcase time-tracking of human radiation and high-resolution imaging. These promising platforms expand the potential of PTE technology into diverse applications, including industry, aerospace, public health, security, and wearable monitoring.

PVK-based LEDs doped by cadmium sulphide nanocrystals coated by mixed thiophenol and 1-decanethiol

Nanoparticles capped with more than one ligand have great potential to improve the properties of optoelectronic devices. To discuss this possibility, we synthesized cadmium sulphide nanocrystals coated by two different ligands, 1-decanethiol and thiophenol. In addition, as a reference, cadmium sulphide nanocrystals coated with thiophenol were synthesized. Photoluminescence and UV–Vis absorption measurements indicated that the maximum emission peaks of both cadmium sulphide nanoparticles were located around 600 nm and the absorption edges showed the existence of two different types of crystalline structure, cubic zinc blende and wurzite-type hexagonal. But the nanoparticles with both ligands had higher emission intensity than nanocrystals coated only by thiophenol. Finally, hybrid light-emitting devices have been manufactured with the following structure: Indium Tin Oxide/Poly(3,4-ethylenedi-oxythiophene): poly(styrene sulfonate)/poly(9-vinylcarbazole): cadmium sulphide/Aluminum. These devices presented an active layer composed of poly(9-vinylcarbazole) doped by cadmium sulphide nanocrystals coated only by thiophenol in one case and with thiophenol and 1-decanethiol in the other case. The inclusion of nanocrystals in the active layer increased the current density of these devices. In addition, the solubility in chlorobenzene of nanoparticles with both ligands was improved, due to the presence of 1-decanethiol on their surface. Moreover, the presence of the second ligand intensified the influence of nanoparticles in electroluminescence measurements compared to cadmium sulfide nanocrystals without 1-decanethiol.

Design, Fabrication, and Characterization of Inkjet-Printed Organic Piezoresistive Tactile Sensor on Flexible Substrate.

In this paper, we propose a novel tactile sensor with a "fingerprint" design, named due to its spiral shape and dimensions of 3.80 mm × 3.80 mm. The sensor is duplicated in a four-by-four array containing 16 tactile sensors to form a "SkinCell" pad of approximately 45 mm by 29 mm. The SkinCell was fabricated using a custom-built microfabrication platform called the NeXus which contains additive deposition tools and several robotic systems. We used the NeXus' six-degrees-of-freedom robotic platform with two different inkjet printers to deposit a conductive silver ink sensor electrode as well as the organic piezoresistive polymer PEDOT:PSS-Poly (3,4-ethylene dioxythiophene)-poly(styrene sulfonate) of our tactile sensor. Printing deposition profiles of 100-micron- and 250-micron-thick layers were measured using microscopy. The resulting structure was sintered in an oven and laminated. The lamination consisted of two different sensor sheets placed back-to-back to create a half-Wheatstone-bridge configuration, doubling the sensitivity and accomplishing temperature compensation. The resulting sensor array was then sandwiched between two layers of silicone elastomer that had protrusions and inner cavities to concentrate stresses and strains and increase the detection resolution. Furthermore, the tactile sensor was characterized under static and dynamic force loading. Over 180,000 cycles of indentation were conducted to establish its durability and repeatability. The results demonstrate that the SkinCell has an average spatial resolution of 0.827 mm, an average sensitivity of 0.328 mΩ/Ω/N, expressed as the change in resistance per force in Newtons, an average sensitivity of 1.795 µV/N at a loading pressure of 2.365 PSI, and a dynamic response time constant of 63 ms which make it suitable for both large area skins and fingertip human-robot interaction applications.

Development of substrate free polymer composite for Pb2+ ion sensor

In the present study we focused on utilizing differential pulse voltammetry (DPV) for detecting Pb2+ ions by electrochemical technique. Polyvinyl butyral (PVB) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) based composite system (PVB/PEDOT:PSS/MoS2) (PPM) modified by Molebdenum disulphide (MoS2). Structural characterization of PPM composite was done by x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, revealing phase transitions and chemical functionalities within the ternary system. E2g and A1g Raman active modes related C α -C β interactions were observed by Raman spectroscopy. Scanning electron microscopy (SEM) forseen uniform filler distribution in homogeneous polymer matrix. Atomic force microscopy (AFM) reveals decreased surface roughness. Sessile drop contact angle measurements were confirmed hydrophilic properties, feasible for sensing applications. Cyclic voltammetry was performed in a 1 M acetate buffer solution, aligned with electrochemical impedance spectroscopy (EIS) results. The sensing capacity of PPM films was examined using differential pulse voltammetry (DPV). Sensor demonstrated effective detection of Pb2+ ions, with a low detection limit (LOD) of 27.77 μM and a linear detection range of 25–60 μM. Developed sensor exhibited excellent repeatability (with relative standard deviation (RSD) 0.6%) and strong selectivity. Sensor electrode performed appriciable trace of Pb2+ ions in drinking water at high concentration.

Novel Modified Styrene-Based Microspheres for Enhancing the Performance of Drilling Fluids at High Temperatures.

Ensuring wellbore stability is of utmost importance for safety when drilling in deep formations. However, high temperatures severely disrupt the drilling fluid gel system, leading to severe stability issues within ultra-deep formations containing micropores. This study focused on the development of a polymer-based plugging material capable of withstanding high temperatures up to 200 °C. A kind of microsphere, referred to as SST (styrene-sodium styrene sulfonate copolymer), was synthesized with a particle size of 322 nm. Compared to polystyrene, the thermal stability of SST is greatly improved, with a thermal decomposition temperature of 362 °C. Even after subjecting SST to hot rolling at 200 °C for 16 h, the particle size, elemental composition, and zeta potential remained stable within an aqueous dispersion system. The results of core displacement and NMR tests demonstrate that SST considerably reduces the pore diameter with a remarkable plugging efficiency of 78.9%. Additionally, when drilling fluids reach 200 °C, SST still enhances drilling fluid suspension and dispersion, and reduces fluid loss by over 36% by facilitating the dispersion of clay particles, improving the gel structure of the drilling fluid, resisting clay dehydration, and promoting plugging. The development of SST provides valuable insights into the preparation of high-temperature-resistant microspheres and the formulation of effective plugging agents for deep-well drilling fluids.

Polymer-nanoparticle thin scaffolds with any-shape magnetic field gradients

This study investigates the self-assembly of magnetic nanoparticles into a flat nanocomposite surface with concealed magnetic patterns. The application of a multilayer stamping medium and the presence of a magnetic field gradient would enable the attraction and organization of superparamagnetic iron oxide nanoparticles (SPIONs) onto predefined areas, corresponding to a pre-fabricated magnetic layer. The experimental approach involved preparing patterned surfaces by applying a multilayer of poly(ethyleneimine) (PEI) and poly(styrene sulfonate) (PSS) as a stamping medium. The SPIONs selectively adhered to the surface, mirroring the underlying magnetic layer shape. Subsequently, these SPION were subjected to an 80 °C treatment in the presence of an external magnetic field to enhance their magnetic properties, and then covered with a polystyrene layer. Using atomic force microscopy, magnetic force microscopy and dark field mode optical microscopy we demonstrated that obtained patterned magnetic field gradients are strong enough to attract and organize magnetic material on top of them, even when being covered with polymeric layers. Moreover, our findings show that the oriented deposition of magnetic nanoparticles is primarily determined by the strength of magnetic interactions between the pattern and nanoparticles, independently of surface topography (with roughness of 0.21 ± 0.06 nm) or Brownian motions.

Enhancing infrared electrochromic properties of the poly(styrene sulfonate) doped polyaniline composite film by morphology regulation

Infrared electrochromic device based on polyaniline (PANI) possesses the ability to regulate infrared radiation, which has a great application prospect in the field of satellite intelligent thermal control. However, it is still challenging to efficiently fabricate uniform and dense PANI functional layer with excellent infrared electrochromic properties. Here, we demonstrate the use of polymer additive to promote deposition of PANI with smooth and dense morphology by inducing uniform electrochemical deposition rate on the electrode surface and inhibiting the growth of PANI in three-dimensional direction through adsorption mechanism. By adding a low concentration of poly(styrene sulfonate) (PSS) to the electrodeposition solution, the PANI film with uniform and compact micromorphology was prepared with excellent infrared electrochromic property, which can realize the modulation of emittance more than 0.4 and 0.45 in the range of 8 ∼ 14 μm and 2.5 ∼ 25 μm, respectively. Furthermore, the infrared electrochromic device that employ the optimized PANI functional film and adsorbing ionic liquid porous gel electrolyte was constructed. Through high and low temperature cycle test (1000 cycles) and vacuum environment test, the device exhibits wonderful durability and can achieve large emissivity modulation in the wavelength range of 2.5 μm ∼ 25 μm (Δε = 0.38). Meanwhile, the transient thermal analysis of the heat dissipating plate attached with the infrared electrochromic device exhibits that the device has an excellent potential for the purposes of efficient thermal management of the satellite.

Efficient and Stable Inverted Perovskite Solar Cell using Potassium Fluoroborate Doped PEDOT:PSS

Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is widely used as a hole transport layer in inverted perovskite solar cells (PSCs) due to its simple fabrication process and high stability. However, there are severe interface defects between PEDOT:PSS and the perovskite layer, leading to poor power conversion efficiency (PCE) of the inverted devices. Herein, a hole transport layer (PEDOT:PSS) doped with potassium fluoroborate is introduced. The aqueous solution of KBF4 diluted with PEDOT:PSS is cleverly utilized to compare with PEDOT:PSS diluted with deionized aqueous solution. X‐ray photoelectron spectroscopy of PEDOT:PSS confirms the reduction of PSS chains and an increase in conductivity after KBF4 doping. Moreover, KBF4 doping promotes crystal growth, resulting in larger grain size of the perovskite film. Additionally, the defects at the PEDOT:PSS/perovskite interface are effectively passivated, suppressing nonradiative recombination. The results show improved short‐circuit current density, open‐circuit voltage, and fill factor, resulting in a PCE of 19.76%, which is a 17.9% enhancement compared to the original device's 16.75%. The optimized device also exhibits long‐term stability exceeding 1000 h, providing a simple and effective strategy for improving the PCE and stability of inverted PSCs.

Preparation, morphology and thermoelectric performance of PEDOT/CuI nanocomposites

Incorporating inorganic nanomaterials into a polymer matrix is one of the most effective ways to create thermoelectric performance for applications where physical flexibility is essential. In this study, flexible thermoelectric nanocomposite films were synthesized by incorporating inorganic copper iodide (CuI) nanosheets as the filler into poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS). The process involved the preparation of bulk CuI from precursors and, subsequently, the nanosheet synthesis by dissolving the bulk CuI in dimethyl sulfoxide (DMSO). The morphology of the nanosheets and the nanocomposite films was thoroughly examined, and the film’s thermoelectric performance was evaluated using a standard thermoelectric measurement system, ZEM-3. The morphological observation revealed a triangular nanosheet geometry for CuI, with an average lateral dimension of ~33 nm. The PEDOT/CuI nanocomposite films were prepared by mixing CuI nanosheets with PEDOT: PSS through ultrasonication and filtration on a PVDF membrane. The film with 6.9 vol% of CuI nanosheets exhibited an electrical conductivity and Seebeck coefficient of 852.07 S·cm-1 and 14.95 µV·K-1, respectively. This resulted in an enhanced power factor of 19.04 µW·m-1·K-2, much higher than the individual composite components. It demonstrated a trend of increasing power factor with the nanosheets up to 6.9 vol% due to improved electrical conductivity. The increase in electrical conductivity can be attributed to the screening effect induced by DMSO, which leads to a conformational change in the PEDOT chains. Furthermore, an optimal fraction of CuI nanosheets also contributes to this conformational change, further enhancing the electrical conductivity.Graphical

Highly bendable and smoke free degradable nanomaterials modified paper based electrochemical biosensor for efficient detection of protein biomarker

Here, we report results of the studies related to the fabrication of nanomaterial modified paper [Whatman paper modified with poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) and Borophene nanosheets] based biosensor for proteinaceous Serum Amyloid A (SAA) biomarker detection. For the fabrication of stable and cost-efficient nanomaterial modified conducting paper, we used simple dip coating method followed by solvent treatment. The incorporation of Borophene nanosheets onto the conducting paper resulted in enhance electrochemical performance, flexibility and signal stability. The flexibility of fabricated electrode is validated via bending and folding studies; it continues to maintain conductivity even after being folded 40 times. Furthermore, this paper sensor may be quickly and properly disposed of by simple burning method without emitting smoke. It was also observed that no any harmful/heavy element was present after disposal of the paper sensor. During fabrication of paper based sensor, anti-SAA was physically immobilized and further bovine serum albumin (BSA) was used to block the non-specific binding sites. To examine structural and morphological features of the synthesized material and the fabricated paper electrodes; X-ray diffraction, transmission electron microscopy, scanning electron microscopy, contact angle, and Fourier-transform infrared spectroscopy were used. The fabricated immunoelectrode (BSA/anti-SAA/Borophene/CP) is highly efficient to detect SAA with ultralow limit of detection of 0.49 ng mL−1, wider linear detection range in between 1 ng mL−1 - 60 µg mL−1 and high durability of 42 days. Finally, SAA protein in spiked serum samples was analyzed using the fabricated immunosensor, and the obtained results show good correlation with the standard SAA protein samples.

Sulfonated polystyrenes: pH and Mg2+-insensitive amphiphilic copolymers for detergent-free membrane protein isolation

Amphiphilic polymers are increasingly applied in the detergent-free isolation and functional studies of membrane proteins. However, the carboxylate group present in the structure of many popular variants, such as styrene-maleic acid (SMA) copolymers, brings limitations in terms of polymer sensitivity to precipitation at acidic pH or in the presence of divalent metal cations. Herein, we addressed this problem by replacing carboxylate with the more acidic sulfonate groups. To this end, we synthesized a library of amphiphilic poly[styrene-co-(sodium 4-styrene sulfonate)] copolymers (termed SSS), differing in their molecular weight and overall polarity. Using model cell membranes (Jurkat), we identified two copolymer compositions (SSS-L30 and SSS-L36) that solubilized membranes to an extent similar to SMA. Interestingly, the density gradient ultracentrifugation/SDS-PAGE/Western blotting analysis of cell lysates revealed a distribution of studied membrane proteins in the gradient fractions that was different than for SMA-solubilized membranes. Importantly, unlike SMA, the SSS copolymers remained soluble at low pH and in the presence of Mg2+ ions. Additionally, the solubilization of DMPC liposomes by the lead materials was studied by turbidimetry, DLS, SEC, and high-resolution NMR, revealing, for SSS-L36, the formation of stable particles (nanodiscs), facilitated by the direct hydrophobic interaction of the copolymer phenyls with lipid acyl chains.

Dip Coating of Water‐Resistant PEDOT:PSS Films Based on Physical Crosslinking

AbstractWater‐resistant poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films are valuable in biomedical applications; however, they typically require crosslinkers to stabilize the films, which can introduce undesired aggregation or phase separation reactions. Herein, a dipping‐based process to prepare PEDOT:PSS films on nonplanar surfaces without crosslinker is developed. Sequential soaking of a dip‐coated PEDOT:PSS film in ethanol and water imparts water resistance to the film. Microscopic and spectroscopic techniques are used to monitor the process and confirm that the ethanol soaking elutes the excess PSS from the film bulk, which stabilizes the film prior to the water‐soaking process. The obtained films act as conductors and semiconductors on curved surfaces, including 3D‐printed objects. A film deposited on a curved surface is successfully applied as the channel layer in a neuromorphic organic electrochemical transistor. This approach can enable integrated bioelectronic and neuromorphic applications that can be readily deployed for facile prototyping.

Structural and Optical Properties of PEDOT: PSS

In recent years, films fabricated from poly (3, 4-ethylenedioxythiophene): poly (4-styrenesulfonate) (PEDOT: PSS) aqueous dispersions have attracted lot of attention due to their exceptional advantages of high transparency in the visible range, excellent thermal stability and aqueous solution processibility. The effect of annealing on the structural, and optical properties of films obtained by the spin coating method on glass substrates has been investigated. This work investigated the impact of second annealing on the structural, and optical properties of poly (3, 4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) thin films. Thin films PEDOT: PSS of about 150 nm thicknesses were deposited by sol-gel method spin coating technique at room temperature. The obtained films were annealed twice: by annealing at 110 °C temperature for 15 min, and at 170 °C within one hour. The films were characterized by X-ray diffraction (XRD), spectroscopic ellipsometry (SE), photoluminescence spectroscopy, and atomic force microscopy (AFM) methods. Studies have shown that second annealing has reduced defects, efficiently.

Sulfonated Hydrogel Formed via CO2-in-Water Emulsion: Potential in Antibiotic Removal.

Herein, a green, carbon dioxide-in-water high-internal-phase emulsion (C/W HIPEs) was developed and stabilized with polyvinyl alcohol (PVA) for the formation of chitosan oligosaccharide/poly(acrylamide-co-sodium 4-styrene sulfonate) [COS/P(AM-co-SSS)] monolithic porous hydrogel. The obtained monolith was characterized via FT-IR and SEM. The SEM patterns depicted that the monoliths were interconnected, the void sizes were 78.5 µm, and the interconnected pore throats were 28 μm approximately. Mechanical measurement results indicated that the maximum compress stress of the monolith could reach 334.4 kPa at 90% strain, and it exhibited good mechanical stability. After 200 cycles of compression, it could still recover its original shape without cracking. The obtained COS-based monolith was selected to remove tetracycline (TC) for evaluating the adsorptive features of the interpenetrating pore-containing monolith. The monolithic COS/P(AM-co-SSS) hydrogel behaved with strong antibiotic adsorption capacity (1600.4 mg/g for TC). The adsorption process agreed well with the pseudo-second-order kinetic and Langmuir isothermal models. In addition, the porous monolith had a strong electrostatic force on TC according to the thermodynamic study. This work provides a green route for the development of novel monolithic hydrogels and highlights its potential application in the treatment of antibiotic-containing wastewater.

Low temperature charge transport study of MWCNT/PEDOT:PSS composites: insulating to metallic regime

Multiwall carbon nanotube (MWCNT)/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) composites have been examined for their temperature and magnetic field dependent conductivity behavior. The conductivity ratio, σ r (σ 300 K/ σ 2 K), is significantly impacted by the sulfuric acid post-treatment of the composites and a slight alteration in MWCNTs loading. By adjusting the loading of MWCNTs in the composites, the charge transport is tuned from insulating to metallic regime. For the low loading of MWCNTs (0.04 wt%), charge transport of the composite lies in the insulating regime and follows a variable range hopping model. At moderate loading of MWCNTs, the transport of the composites lies in the critical regime and the temperature dependent conductivity follows a power law model. As the MWCNTs loading increases to 4 wt%, transport of the composites shifts to the metallic regime with σ r ∼ 2.8. The temperature dependent conductivity has been explained by using electron-electron interactions and weak localization effects and the conductivity follows ∼T 1/2 and ∼T 3/4 dependence in different temperature regimes. Wave function shrinkage and forward interference effects have been used to evaluate the magnetoconductance (MC) of the samples located in the insulating regime. For the composites lying in the metallic regime, a dominant contribution from weak localization explains the behaviour of the MC. However, for those in the critical regime a combined effect of weak localization and electron-electron interactions has been observed.

Redox Polymer-Regulated Hysteresis in Ion Current Rectification through AAO Membranes and Single Nanopipettes

Nanopore technology has promising potential in fields such as high-density energy conversion, stochastic chemical sensing, logic operation and neuromorphic computing, separation and fundamental nanoelectrochemistry due to its rich ion transport features and easy fabrication. Understanding the ion transport dynamics at the solid-liquid interface is essential for further technological advancements. Ion current rectification (ICR) and its time-dependent hysteresis have been found to arise from the asymmetric nanointerfaces (geometry, together with surface charges in polarity and density). While various nanostructures can be fabricated and surface charges can be modified, active controls in ICR and hysteresis during transport applications are lacking. Here, we report actively controlled transport hysteresis in ion current rectification though PEDOT-modified single nanopipettes and anodic aluminum oxide (AAO) membranes. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) provides high conductivity and chemical stability, low operating voltages, and enhanced performances in hydrophilicity, processability, and flexibility. The PEDOT:PSS aqueous dispersion is crosslinked inside a nanopipette or assembled onto one side of the AAO surface. Oxidation and reduction reversibly switch the PEDOT between the positive and neutral form, and thus modulate the space charge in nanopores or across the AAO membranes, correspondingly, the ion transport behaviors. The amplitude and polarity of ICR and the scale of hysteresis through a nanopore or AAO membrane have been altered by oxidizing/reducing the PEDOT substrate by adjusting the external electrical field. In contrast, the surface charge varying on pH, ionic strength, and electrolyte type is commonly adopted in ion transport studies but cannot be externally regulated in real-time. Interestingly, negative differential resistance (NDR) is also found in the PEDOT-modified nanopores in simple KCl systems without external pressure differential or concentration gradients. The NDR peak position and magnitude can be easily adjusted by controlling the redox states of the PEDOT fillings. Figure 1

Carrier transport and Negative differential resistance of electrically bipolar devices based on poly(3,4-ethylene-dioxythiophene): Poly (styrene sulfonate) film

A poly (3,4-ethylene-dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) film sandwiched between copper electrodes was used to create an electrically bipolar device using a conventional casting technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray spectroscopy (EDX) were used to investigate the structure, morphological behaviour, and homogeneous distribution of PEDOT conducting grains in the insulator matrix PSS. The device exhibits normal hysteretic electrical behaviour and a negative differential resistance (NDR) effect in the swept current-voltage (I–V) curves. By varying the PEDOT:PSS films' positive charge voltage and charging rate, the NDR effect may be tuned. A maximum current ratio of 103 can exist between the High Conducting State (HCS) and the Low-Conducting State (LCS). Complex impedance measurements of the Cu/PEDOT:PSS/Cu device were carried out at applied ac-voltage amplitude, Vac, range from 0.1 V to 2 V and over the frequency range from 100 Hz to 10 MHz at room temperature. Different models based on ac and dc experimental data are used to characterize and confirmed the carrier transport processes in the HC, LC-States and NDR.

Economy and colors based on solution-process rGO-TiO2 dye-sensitized solar cells modulated with organic Fabry-Perot cavity for indoor photovoltaic

This research modified a porous titanium dioxide (TiO2) dye-sensitized solar cell (DSSC) with reduced graphene oxide (rGO) to improve efficiency. A secondary color selectivity effect was obtained by addition of an organic Fabry-Perot (F.P.) cavity. The TiO2 was doped with a variety of rGO including 0, 1, 5, and 10 wt%. Small molecule (McFarland and Tang, 2003; McFarland and Tang, 2003) [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and polymer poly(3,4-ethylenedioxyselenophene): poly (styrene sulfonate) (PEDOS: PSS) were used to create the F.P. cavity. Such organic F.P. cavities on DSSCs can be produced by solution process which is economical, rapid, and produces a large surface area. The devices are suitable for use under low illumination indoor photovoltaic because there is light conversion current under low voltage. The solution process had three parts: (i) using a modified Hummers' method, the rGO was doped onto the porous TiO2 structure in different wt%, (ii) the polymer PEDOT: PSS and small molecule PCBM F.P cavities with different thicknesses were produced, as the thicknesses correspond to different color bands, and (iii) combine the F.P. cavity and rGO-TiO2 to produce a FTO/TiO2-rGO/Dye/Ag/F.P./Ag DSSC. Scanning electron microscope (SEM) images showed that 5 wt% rGO offered the best sheet nano-structure, and this increased the efficiency of DSSC by 28.1% when measured by power conversion efficiency (PCE). The color output advantages of F.P. cavity using PCBM and PEDOT materials are red and blue, respectively. The devices with PEDOT: PSS and PCBM saw a 9 and 12.5% gain compare to DSSC without F.P. cavity. However, two structures of TiO2 doped 5 wt% rGO and colorful PCBM F.P. cavity can increase the efficiency of DSSC by 44.1%.

Enhanced performance of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/silicon solar cells employing inverted pyramidal silicon by one-step copper catalyzed etching

Here, micro-inverted pyramid structured silicon (Si) surface is prepared via simple yet effective, low-cost one-step copper catalyzed chemical etching (CuCCE) for superior light trapping. The inverted pyramidal (IP) arrays are obtained on large area of the partial polished (PP) Si surface by CuCCE in etch bath consisting of Cu(NO3)2/HF/H2O2 at 50 °C. The IP-Si shows significantly reduced total surface reflectance (<7%) than the PP-Si (>30%) for broad spectral range. Hybrid solar cells (HSCs), having junction between poly(3,4-ethylenedioxy thiophene):poly(styrene sulfonate)(PEDOT:PSS) and n-Si, are demonstrated on the IP-Si and PP-Si surfaces; named as IP-SC and PP-SC respectively. Direct enhancement of ∼3 fold in efficiency is observed for IP-SC than the PP-SC. The improved performance is attributed to enhanced light trapping ability of the IP-Si leading to the improved short circuit current density of ∼32 mA/cm2, ∼1.3 times higher than the PP-SC. The HSCs on CuCCE IP-Si surface is presented as a ‘proof of concept’ for future high efficiency devices.