Conductive Plastic Substrates Research Articles

Passivation of perovskite layer surface states with pyridine in flexible and printed perovskite solar cells

Perovskite solar cells (PSCs), prepared by using solution-processed printing techniques, gained much attention over the past few years and a considerable progress has been achieved in improving the power conversion efficiencies of these devices. Nevertheless, there are still some advancements that can be implemented, especially in terms of passivation of surface defects in the perovskite photoactive layer. Passivation can afford considerable reduction in surface recombination of charge carriers in the photoactive layer and help to obtain devices with better performance. In this work, poly(3-hexylthiophene-2,5-diyl)-based inks with small amount of pyridine as an additive are used to deposit the hole transport layer and simultaneously passivate the surface defects of the perovskite layer in flexible and printed PSCs. The devices are fabricated on flexible conductive plastic substrates using a slot-die coating method. It is found that 2.5 wt.% pyridine-containing inks for preparing hole transport layer have a positive effect on the performance of resulting PSCs. On average, around 13% improvement in the power conversion efficiency is observed for the devices with passivation as opposed to the reference devices without passivation. The effect of pyridine passivation on the structural and electronic properties of the perovskite layer on a flexible substrate is studied using experimental and analytical techniques, whereas the computer simulation methods are employed to rule out the possible mechanisms for the performance improvements in the devices with passivation. The approach presented here can be useful for developing simplified protocols for printing of flexible PSCs with the passivated perovskite layer and improved device efficiency.

Development of ZNR-calcium biosensor application

For sensitive biosensor fabrication, zinc oxide nanorods were coated with calcium ionophore membranes to detect ions concentration. For preparing samples two different layers were deposited by consecutively using two different methods: the former method was the sol-gel method and the later one was the aqueous chemical growth (ACG) method. Biosensors with four different substrate kinds, conducting plastic substrate (P), silicon substrate (S), silver wire substrate (W) and borosilicate glass capillary tube tip substrate (T) were used as working electrodes for calcium concentration determination biosensor were initially checked potentiometrically in two solutions: the solution ranging between 100 mM and 100 nM and cells serum in human blood. Four prepared working electrodes morphologies and structures were characterized by field emission high resolution scanning electron microscopy.

Zinc oxide nano-rods based glucose biosensor devices fabrication

Abstract ZnO is distinguished multifunctional material that has wide applications in biochemical sensor devices. For extracellular measurements, Zinc oxide nano-rods will be deposited on conducting plastic substrate with annealing temperature 150 °C (ZNRP150) and silver wire with annealing temperature 250 °C (ZNRW250), for the extracellular glucose concentration determination with functionalized ZNR-coated biosensors. It was performed in phosphate buffer saline (PBS) over the range from 1 µM to 10 mM and on human blood plasma. The prepared samples crystal structure and surface morphologies were characterized by XRD and field emission scanning electron microscope FESEM respectively.

Tailoring morphology and thickness of perovskite layer for flexible perovskite solar cells on plastics: The role of CH3NH3I concentration

A smooth perovskite film fully covering the substrate is of importance for flexible perovskite solar cells (PSCs). In this study, efficient flexible PSCs are fabricated onto conductive plastic substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH3NH3I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM and AFM analysis, which consequently gives rise to a thin perovskite layer with smooth surface and smaller grain size. As a result, flexible PSCs with efficiency of 12.7% are prepared under ambient condition, and the excellent mechanical stability of flexible PSCs is also demonstrated with bending test under severe conditions.

Influence of Acid Modification Multiwall Carbon Nanotube Counter Electrodes on the Glass and Flexible Dye-Sensitized Solar Cell Performance

Multiwall carbon nanotubes (MWCNTs) were modified by acids (H2SO4 : HNO3) for generating active groups on the nanotube surface. Unmodified- and modified-carbon nanotubes were coated on the conductive glass and conductive plastic substrates by a slurry paste method, and they were used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Scanning electron microscopy reveals that carbon nanotubes are evenly deposited on the conductive glass. The efficiency of the glass based DSSCs of unmodified- and modified-carbon nanotubes and Pt CEs is ~4.73%, ~5.66%, and ~6.08%, respectively. The efficiency of the plastic based DSSCs of the unmodified- and modified-carbon nanotubes CEs is ~0.80% and ~2.11%, respectively. The voltammogram and electrochemical impedance spectroscopy results suggest that the superior performance of the modified-carbon nanotubes DSSCs is attributable to the high electrocatalytic activity and the low charge-transfer resistance of the modified-carbon nanotubes film over the unmodified-carbon nanotubes film.

A gold surface plasmon enhanced mesoporous titanium dioxide photoelectrode for the plastic-based flexible dye-sensitized solar cells

The gold nanoparticles inlaid mesoporous titania nanoparticles (Au@MTNs) thin films are fabricated on a conductive plastic substrate by using a low-temperature electrophoretic deposition (EPD) process followed by a compression post-treatment. The obtained Au@MTNs electrode exhibits an excellent light trapping because of the formation of surface plasmons on the Au nanoparticles (NPs). The flexible Au@MTNs electrodes are applied for the photoanodes in all-plastic-based dye-sensitized solar cells (DSSCs). The Au@MTNs photoanodes containing various wt% of Au NPs are prepared in order to optimize the performance of the DSSCs. When 0.8 wt% of Au NPs is used in the Au@MTNs photoanode, a power conversion efficiency (η) of 5.62% is achieved under the illumination of 100 mW cm−2, which exhibits a 14% increase compared to the DSSC fabricated with pure a titanium dioxide (TiO2) photoanode (4.93%); this enhancement is attributed to the plasmonic light trapping provided by the Au NPs.

Electrochemical deposition of molybdenum sulfide thin films on conductive plastic substrates as platinum-free flexible counter electrodes for dye-sensitized solar cells

In this study, pulsed electrochemical deposition (pulsed ECD) was used to deposit molybdenum sulfide (MoSx) thin films on indium tin oxide/polyethylene naphthalate (ITO/PEN) substrates as flexible counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The surface morphologies and elemental distributions of the prepared MoSx thin films were examined using field-emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy. The chemical states and crystallinities of the prepared MoSx thin films were examined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The optical transmission (T (%)) properties of the prepared MoSx samples were determined by ultraviolet–visible spectrophotometry. Cyclic voltammetry (CV) and Tafel-polarization measurements were performed to analyze the electrochemical properties and catalytic activities of the thin films for redox reactions. The FE-SEM results showed that the MoSx thin films were deposited uniformly on the ITO/PEN flexible substrates via the pulsed ECD method. The CV and Tafel-polarization curve measurements demonstrated that the deposited MoSx thin films exhibited excellent performances for the reduction of triiodide ions. The photoelectric conversion efficiency (PCE) of the DSSC produced with the pulsed ECD MoSx thin-film CE was examined by a solar simulator. In combination with a dye-sensitized TiO2 working electrode and an iodine-based electrolyte, the DSSC with the MoSx flexible CE showed a PCE of 4.39% under an illumination of AM 1.5 (100mWcm−2). Thus, we report that the MoSx thin films are active catalysts for triiodide reduction. The MoSx thin films are prepared at room temperature and atmospheric pressure and in a simple and rapid manner. This is an important practical contribution to the production of flexible low-cost thin-film CEs based on plastic substrates. The MoSx thin films produced by pulsed ECD are good candidates for catalysts in flexible DSSCs.

Thickness-controllable textured TiO2 underlayer for a flexible dye-sensitized solar cell sub-module

Incorporating a thin underlayer as a barrier interface between nanocrystalline TiO2 and conducting substrate suppresses recombination loss in dye-sensitized solar cells (DSSCs). The study investigates the effect of the thickness of the textured underlayer on the optical properties, photovoltaic performance, and electron-transporting properties. The photocurrent of the Ti foil-based photoanode exhibits a strong dependence on underlayer thickness. A homogeneous Pt counter electrode with superior catalytic ability is prepared by spraying onto a conducting plastic substrate. A flexible DSSC sub-module using Ti foil-based photoanode with an optimized thickness underlayer, and a plastic substrate counter electrode with sprayed-reduced Pt, has an energy-conversion efficiency of 7.10%.

A45 TRAINED AND NON-TRAINED MEDICAL PROFESSIONAL: EFFECTIVENESS AND VARIABILITY OF MANUAL VENTILATION IN NEONATAL RESUSCITATION USING TWO DEVICES

This report shows that flexible dye-sensitized solar cell can be fabricated by a laser-detachment and press method where the TiO2 electrode typically sintered on glass source substrate is detached by a laser pulse and then is firmly adhered to the conductive plastic substrate by applying a high pressure. The cells fabricated by this process exhibited 36–43% smaller photocurrent and efficiency than the conventional glass cells with directly coated TiO2 electrodes. It was attributed to the lowered dye coverage and electron diffusion length, both of which originate from the press-induced reduction of TiO2 porosity. A maximum efficiency of 5.68% was obtained for the plastic cell. Bending of the electrode led to 20% loss of the current density and efficiency. However, no further performance degradation was observed even when the bending cycle was increased to 100, 300, and 500 times. This indicates that the bending-induced degradation of TiO2 electrode on the plastic substrate takes place at the first bending.

Preparation of High Performance Pt Counter Electrodes on Conductive Plastic Substrate for Flexible Dye-Sensitized Solar Cells

Pt counter electrodes (CE) were been prepared using ion sputtering method on indium-doped tinoxide coated polyethylene terephthalate (ITO-PET) for flexible dye-sensitized solar cells (DSSCs). The effect of sputtering time on the properties was characterized by Feld emission scanning electron microscope (FESEM), electrochemical impedance (EIS) and UV-vis absorption spectra. The flexible CE show increased catalytic activity but reduced transmittance when the sputtering time is increased from 0 to 80 s. The light-to-electricity conversion efficiency of the DSSCs assembled with the high catalytic activity flexible CE attained a conversion efficiency of 4.0% by using Ti foil as the photoanode substrate under the simulated AM 1.5 sunlight. The results reveal that ion sputtering is an effective method for depositing platinum nanoparticles on plastic substrates with low cost under room-temperature.

Simple Method for Manufacturing Pt Counter Electrodes on Conductive Plastic Substrates for Dye-Sensitized Solar Cells

A novel, facile, and low-cost method was developed for manufacturing Pt counter electrodes (CEs) of dye-sensitized solar cells (DSCs) on the indium tin oxide-coated polyethylene terephthalate (ITO-PET). This press-transferring method reconciled the temperature conflict between the sintering process of thermal decomposition of H(2)PtCl(6) and plastic substrates. Cyclic voltammograms, electrochemical impedance spectroscopy, transmittance spectra and photovoltaic performance were characterized to investigate the transferred Pt CEs. It was found that the transferred Pt CEs on ITO-PET exhibited an excellent catalytic activity comparable with traditional electrodes on FTO glasses. On the front-side, an illuminated conversion efficiency of 7.21% was reached with more than 94% efficiency of conventional thermally deposited Pt CEs on FTO glasses, and on the back-side, the illuminated conversion efficiency was 4.86%, which was higher than that for conventional electrodes.

Flexible dye-sensitized solar cell fabricated on plastic substrate by laser-detachment and press method

This report shows that flexible dye-sensitized solar cell can be fabricated by a laser-detachment and press method where the TiO2 electrode typically sintered on glass source substrate is detached by a laser pulse and then is firmly adhered to the conductive plastic substrate by applying a high pressure. The cells fabricated by this process exhibited 36–43% smaller photocurrent and efficiency than the conventional glass cells with directly coated TiO2 electrodes. It was attributed to the lowered dye coverage and electron diffusion length, both of which originate from the press-induced reduction of TiO2 porosity. A maximum efficiency of 5.68% was obtained for the plastic cell. Bending of the electrode led to 20% loss of the current density and efficiency. However, no further performance degradation was observed even when the bending cycle was increased to 100, 300, and 500 times. This indicates that the bending-induced degradation of TiO2 electrode on the plastic substrate takes place at the first bending.

Plastic based dye-sensitized solar cells using Co9S8 acicular nanotube arrays as the counter electrode

Novel one-dimensional (1D) Co9S8 acicular nanotube arrays (ANTAs) are fabricated on a conducting plastic substrate by a two-step approach. Layered cobalt carbonate hydroxide (Co(CO3)0.5(OH)x·11H2O, LCCH) acicular nanorod arrays (ANRAs) are fabricated on a conducting plastic substrate by chemical bath deposition (CBD), followed by a simple ionic-exchange process to convert the LCCH ANRAs into Co9S8 ANTAs. The compositions of the films are verified by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) mapping; their morphologies are examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The films of Co9S8 ANTAs, obtained after various periods of the CBD, are analyzed by cyclic voltammetry (CV) measurements and Tafel polarization curves, and the Co9S8 ANTAs obtained from 150 min of CBD show higher electrocatalytic ability towards the I−/I3− reaction than sputtered Pt. In addition, the long-term stability of the Co9S8 ANTAs film in I−/I3− electrolyte was tested by CV. The plastic based Co9S8 ANTAs electrodes are used as the counter electrodes (CEs) of flexible dye-sensitized solar cells (DSSCs), and a high power conversion efficiency of 5.47% is achieved, which is comparable to that of the DSSC using sputtered Pt (5.62%). Therefore, the Co9S8 ANTAs are proposed to be a reliable material to replace Pt as plastic based CEs of DSSCs.

Composite Films Based on Poly(3,4-ethylene dioxythiophene):Poly(styrene sulfonate) Conducting Polymer and TiC Nanoparticles as the Counter Electrodes for Flexible Dye-Sensitized Solar Cells

A composite film of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and titanium carbide nanoparticles (TiC-NPs) was deposited on an indium doped tin oxide–poly(ethylene naphthalate) (ITO–PEN) conducting plastic substrate by a doctor blade technique. This ITO–PEN substrate with the composite film was used as the flexible counter electrode (CE) for a plastic dye-sensitized solar cell (DSSC). Performances of the plastic DSSC with the platinum-free CEs containing PEDOT:PSS/TiC-NPs composite was investigated. A solar-to-electricity conversion efficiency (η) of 6.50% was achieved for the pertinent DSSC with PEDOT:PSS/TiC-NPs composite, using commercial N719 dye, which exhibited comparable performance to that of a cell with a sputtered-Pt film on its CE (6.84%). The homogeneous nature of the composite film PEDOT:PSS/TiC-NPs, the uniform distribution of TiC-NPs in its PEDOT:PSS matrix, and the large electrochemical surface area of the composite film are seen to be the factors for the best performance of the pertinent DSSC. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the TiC-NPs. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize the films. The high efficiency of the cell with PEDOT:PSS/TiC-NPs is explained by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and incident photon-to-current conversion efficiency (IPCE) curves.

Low-cost, quasi-solid-state and TCO-free highly bendable dye-sensitized cells on paper substrate

A highly conductive Ni-coated commercial paper substrate (square resistance <1 Ω) was prepared by chemical deposition, and used as the substrate for a flexible TiO2 film electrode derived from a binder-free TiO2 paste, and heat treated at 250 °C. A low-cost, quasi-solid-state and TCO-free highly bendable paper-based dye-sensitized solar cell with conversion efficiency up to 2.90% is fabricated successfully by applying an iodine-free electrolyte. This encouraging result indicates that commercial paper is a promising material for use in dye-sensitized solar cells because of its flexibility, low cost and relatively high resistance to temperature. Compared with the rigid transparent conducting oxide (TCO) coated glass and flexible conductive plastic substrates, the potential of using mature paper making and coating technologies will greatly reduce the cost of the current photovoltaic devices.

A novel preparation of small TiO2 nanoparticle and its application to dye-sensitized solar cells with binder-free paste at low temperature

TiO(2) nanoparticles with diameter <10 nm were synthesized by a facile, non-hydrothermal method at low temperature. A porous TiO(2) film electrode consisting of the obtained small TiO(2) nanoparticles and commercial TiO(2) nanoparticles without any organic binder was prepared at low temperature. The photovoltaic performance of the solar cell based on the TiO(2) electrode was investigated by the current-voltage and electrochemical impedance spectra. All the experimental results indicate that the addition amount of the small TiO(2) nanoparticles in the binder-free paste affects the photovoltaic performance of the photoelectrode greatly. The overall energy conversion efficiency of the optimized binder-free photoelectrode achieves 3.53% without high-temperature sintering. Additionally, the performance of the small particles derived from this facile method can be comparable with that of small ones obtained from traditionally hydrothermal method, indicating the small particles in our study can be applied to flexible dye-sensitized solar cells. And the present low-temperature preparation of photoelectrode containing small TiO(2) nanoparticles shows an encouraging performance on both conductive glass and plastic substrates and could be suited in the industrial and large-scale application due to its low energy cost and relatively high conversion efficiency.

Ultra-Thin TiO2 Layers for Enhancing the Conversion Efficiency of Flexible Dye-Sensitized Solar Cells

Ultra-thin TiO2 film was deposited on transparent conductive plastic substrates for use as a compact layer in flexible dye-sensitized solar cells (FDSCs). We evaluate the effects of various sputter working gases on the characteristics and blocking efficacy of the resulting films. Although the phases of the TiO2 films deposited under different gases are all different, they all provide effective blocking to reduce the dark current and enhance the fill factor. With the use of these sputter-deposited compact layers, we show that the overall power conversion efficiency can be increased by 25 to 30%. The result demonstrates a facile and roll-to-roll compatible process for the improvement of photovoltaic performance and the design of lightweight plastic-substrate FDSCs.

Comparison of PEDOT Films Obtained via Three Different Routes through Spectroelectrochemistry and the Differential Cyclic Voltabsorptometry Method (DCVA)

The performance of different poly(3,4-ethylenedioxythiophene) (PEDOT) films was compared by electrochemical, spectroelectrochemical, and time-derivative measurements of absorbance versus potential (linear potential-scan voltabsorptometry) for an overall spectroelectrochemical characterization of the electrochromic properties in ionic liquids such as 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI). The time-derivative signals were monitored at different wavelengths, and information obtained therefrom was complementary to that obtained from conventional cyclic voltammetry. PEDOT films prepared via in situ chemical oxidative polymerization appeared to be much more efficient than electropolymerized and PEDOT-poly(styrenesulfonate) (PSS) reference films, in terms of both contrast ratio and coloration efficiency, which was the case even for PEDOT films deposited on less conductive flexible plastic substrates.

Fabrication of high performance Pt counter electrodes on conductive plastic substrate for flexible dye-sensitized solar cells

Pt counter electrodes (CEs) with different platinum loading have been prepared using chemical reduced method on flexible indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) for dye-sensitized solar cells (DSSCs). H 2PtCl 6·6H 2O terpineol solutions were screen printed on the transparent ITO-PEN substrates. After drying, H 2PtCl 6 was reduced by treating it in NaBH 4 solution followed by the hydrothermal treatment at 100 °C. The obtained Pt CEs with different Pt-loading (2.4–7.7 μg/cm 2) were characterized by SEM, XPS, electrochemical impedance and transmission spectrum measurement. The Pt CEs show high catalytic activity, low charge transfer resistance (0.26–1.38 Ω cm 2) and good light transmittance (about 70% at 400–800 nm). The light-to-electricity conversion efficiency of the flexible DSSC fabricated with the prepared Pt CE and the TiO 2 photoanode prepared on Ti substrate by screen printing technique attains 5.41% under the simulated AM 1.5 sunlight, which is almost same as that based on the thermal decomposited Pt CE on FTO-glass. Compared with other methods to prepare Pt CEs, chemical reduced method is simple and suitable for flexible polymer substrates and the large scale preparation of DSSCs.

Dynamic preparation of TiO 2 films for fabrication of dye-sensitized solar cells

Preparation of nanocrystalline porous titanium dioxide (TiO 2) films with roll-to-roll compatible methods was studied. Gravure printing was used for spreading TiO 2 paste and paper calendering for pressing TiO 2 nanoparticle films. Influence of different preparation methods on performance of fabricated dye-sensitized solar cells (DSSCs) was investigated. The attained light into electricity conversion efficiency was compared with DSSCs fabricated on conductive plastic substrates by doctor-blading spreading with subsequent static pressing. The latter method achieved a light conversion efficiency as high as 5.1%. The efficiency of the cells with a gravure printed TiO 2 film was found to be rather low. The highest conversion efficiency was 1.7%; this is concluded to be due to insufficient thickness of the gravure printed TiO 2 films. Calendering of the doctor-bladed films on the other hand attained a light conversion efficiency of 4.7%.