Showing papers on "Indium tin oxide published in 2010"
TL;DR: The roll-to-roll production and wet-chemical doping of predominantly monolayer 30-inch graphene films grown by chemical vapour deposition onto flexible copper substrates are reported, showing high quality and sheet resistances superior to commercial transparent electrodes such as indium tin oxides.
Abstract: The outstanding electrical, mechanical and chemical properties of graphene make it attractive for applications in flexible electronics. However, efforts to make transparent conducting films from graphene have been hampered by the lack of efficient methods for the synthesis, transfer and doping of graphene at the scale and quality required for applications. Here, we report the roll-to-roll production and wet-chemical doping of predominantly monolayer 30-inch graphene films grown by chemical vapour deposition onto flexible copper substrates. The films have sheet resistances as low as approximately 125 ohms square(-1) with 97.4% optical transmittance, and exhibit the half-integer quantum Hall effect, indicating their high quality. We further use layer-by-layer stacking to fabricate a doped four-layer film and measure its sheet resistance at values as low as approximately 30 ohms square(-1) at approximately 90% transparency, which is superior to commercial transparent electrodes such as indium tin oxides. Graphene electrodes were incorporated into a fully functional touch-screen panel device capable of withstanding high strain.
7,709 citations
TL;DR: In this paper, a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance.
Abstract: We report a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance. We utilized a synthesis specifically designed for long and thin wires for improved performance in terms of sheet resistance and optical transmittance. Twenty Ω/sq and ∼80% specular transmittance, and 8 ohms/sq and 80% diffusive transmittance in the visible range are achieved, which fall in the same range as the best indium tin oxide (ITO) samples on plastic substrates for flexible electronics and solar cells. The Ag NW electrodes show optical transparencies superior to ITO for near-infrared wavelengths (2-fold higher transmission). Owing to light scattering effects, the Ag NW network has the largest difference between diffusive transmittance and specular transmittance when compared with ITO and carbon nanotube electrodes, a property which could gr...
1,950 citations
TL;DR: CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138 degrees, whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60 degrees, indicating the great potential of CVD graphene films for flexible photovoltaic applications.
Abstract: We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness (∼0.9 nm) and offered sheet resistance down to 230 Ω/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (η) of 1.18 and 1.27%, respectively. Further...
1,141 citations
TL;DR: Graphene applications are just starting, and current investigations are on a number of areas such as composites, nanoelectronics, and transparent electrodes, where a continuous single-layer graphene fi lm could retain high conductivity at very low (atomic) thickness, and avoid contact resistance that occurs in a carbon nanotubes between interconnected nanotube bundles.
Abstract: www.MaterialsViews.com C O M Graphene-On-Silicon Schottky Junction Solar Cells M U N I By Xinming Li , Hongwei Zhu , * Kunlin Wang , * Anyuan Cao , Jinquan Wei , Chunyan Li , Yi Jia , Zhen Li , Xiao Li , and Dehai Wu C A IO N Graphene, a single atomic layer of carbon hexagons, has stimulated a lot of research interest owing to its unique structure and fascinating properties. [ 1 ] Graphene has been produced in the form of ultrathin sheets consisting of one or a few atomic layers by chemical vapor deposition (CVD) [ 2–4 ] or solution processing [ 5 , 6 ] and can be transferred to various substrates. The two-dimensionality and structural fl atness make graphene sheets ideal candidates for thin-fi lm devices and combination with other semiconductor materials such as silicon. These fi lms typically show sheet resistances on the order of several hundred ohm per square at about 80% optical transparency. [ 7 ] With modifi cation on the electronic properties and improvement of processing techniques, graphene fi lms show potential for use in conductive, fl exible electrodes, as an alternative for indium tin oxide (ITO). Graphene applications are just starting, and current investigations are on a number of areas such as fi llers for composites, nanoelectronics, and transparent electrodes. [ 8 ] For applications related to solar cells, graphene microsheets were dispersed into conjugated polymers to improve exciton dissociation and charge transport. [ 9–11 ] Also, solution-processed thin fi lms were used as conductive and transparent electrodes for organic [ 12 ] and dyesensitized [ 13 ] solar cells, although the cell effi ciency is still lower than those with ITO and fl uorine tin oxide (FTO) electrodes. Compared with carbon nanotube fi lms that have been extensively studied, graphene fi lms may have several advantages. A continuous single-layer graphene fi lm could retain high conductivity at very low (atomic) thickness, and avoid contact resistance that occurs in a carbon nanotube fi lm between interconnected nanotube bundles. In addition, graphene fi lms have minimum porosity and, in small areas, can provide an extremely fl at surface for molecule assembly and device integration. There are many opportunities in utilizing distinct properties of graphene and exploring novel applications. Bulk heterojunction structures based on carbon materials have attracted a great deal of interest for both scientifi c fundamentals and potential applications in various new optoelectronic devices,
1,070 citations
TL;DR: The results indicate that GO could be a simple solution-processable alternative to PEDOT:PSS as the effective hole transport and electron blocking layer in OPV and light-emitting diode devices.
Abstract: The utilization of graphene oxide (GO) thin films as the hole transport and electron blocking layer in organic photovoltaics (OPVs) is demonstrated. The incorporation of GO deposited from neutral solutions between the photoactive poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) layer and the transparent and conducting indium tin oxide (ITO) leads to a decrease in recombination of electrons and holes and leakage currents. This results in a dramatic increase in the OPV efficiencies to values that are comparable to devices fabricated with PEDOT:PSS as the hole transport layer. Our results indicate that GO could be a simple solution-processable alternative to PEDOT:PSS as the effective hole transport and electron blocking layer in OPV and light-emitting diode devices.
719 citations
TL;DR: High-performance transparent electrodes with copper nanofiber networks as transparent electrodes are shown by a low-cost and scalable electrospinning process and have a power efficiency comparable to devices made with ITO electrodes.
Abstract: Transparent electrodes, indespensible in displays and solar cells, are currently dominated by indium tin oxide (ITO) films although the high price of indium, brittleness of films, and high vacuum deposition are limiting their applications. Recently, solution-processed networks of nanostructures such as carbon nanotubes (CNTs), graphene, and silver nanowires have attracted great attention as replacements. A low junction resistance between nanostructures is important for decreasing the sheet resistance. However, the junction resistances between CNTs and boundry resistances between graphene nanostructures are too high. The aspect ratios of silver nanowires are limited to ∼100, and silver is relatively expensive. Here, we show high-performance transparent electrodes with copper nanofiber networks by a low-cost and scalable electrospinning process. Copper nanofibers have ultrahigh aspect ratios of up to 100000 and fused crossing points with ultralow junction resistances, which result in high transmitance at low sheet resistance, e.g., 90% at 50 Ω/sq. The copper nanofiber networks also show great flexibility and stretchabilty. Organic solar cells using copper nanowire networks as transparent electrodes have a power efficiency of 3.0%, comparable to devices made with ITO electrodes.
697 citations
TL;DR: Random silver nanowire (AgNW) networks show optoelectronic performances very close to that of ITO and are regarded as the leading candidate material to replace ITO.
Abstract: With the emergence of fl exible plastic devices and the scarcity of indium resources, great efforts have been made to develop new fl exible transparent conductors to replace indium tin oxide (ITO), [ 1,2 ] examples including conductive polymers, [ 3,4 ] carbon nanotubes (CNTs), [ 5–8 ] graphene, [ 9 ] metal grids, [ 10 ] and random networks of metallic nanowires. [ 11,12 ] Among these contenders, random silver nanowire (AgNW) networks show optoelectronic performances very close to that of ITO [ 11 , 13 ] and are regarded as the leading candidate material to replace ITO [ 14 ] (Table 1S in Supporting Information). There are two critical issues that currently prohibit AgNW fi lms from large scale applications: AgNW fi lms deposited on bare substrates are highly coarse [ 12 ]
548 citations
TL;DR: Graphene hybrid with carbon nanotubes may prove to be especially interesting as discussed by the authors, as it may be suitable for many electronic applications including as a transparent conductor, and has been shown to be useful in the synthesis and characterization of graphene.
507 citations
TL;DR: A method for obtaining unity-order refractive index changes in the accumulation layer of a metal-oxide-semiconductor heterostructure with conducting oxide as the active material with plasmonic mode is reported.
Abstract: We report a method for obtaining unity-order refractive index changes in the accumulation layer of a metal-oxide-semiconductor heterostructure with conducting oxide as the active material Under applied field, carrier concentrations at the dielectric/conducting oxide interface increase from 1 × 10^(21)/cm^3 to 28 × 10^(22)/cm^3, resulting in a local refractive index change of 139 at 800 nm When this structure is modeled as a plasmonic waveguide, the change corresponds to a modal index change of 008 for the plasmonic mode
482 citations
TL;DR: The p-type doping behavior was confirmed by characterizing the Raman G-band of the doped graphene film and the doping effect was manifested only with 1-2 layer graphene but not with multi-layer graphene, advancing the numerous applications of graphene films as transparent conducting electrodes.
Abstract: We report chemical doping (p-type) to reduce the sheet resistance of graphene films for the application of high-performance transparent conducting films. The graphene film synthesized by chemical vapor deposition was transferred to silicon oxide and quartz substrates using poly(methyl methacrylate). AuCl(3) in nitromethane was used to dope the graphene films and the sheet resistance was reduced by up to 77% depending on the doping concentration. The p-type doping behavior was confirmed by characterizing the Raman G-band of the doped graphene film. Atomic force microscope and scanning electron microscope images reveal the deposition of Au particles on the film. The sizes of the Au particles are 10-100 nm. The effect of doping was also investigated by transferring the graphene films onto quartz and poly(ethylene terephthalate) substrates. The sheet resistance reached 150 Omega/sq at 87% transmittance, which is comparable to those of indium tin oxide conducting film. The doping effect was manifested only with 1-2 layer graphene but not with multi-layer graphene. This approach advances the numerous applications of graphene films as transparent conducting electrodes.
381 citations
TL;DR: In this article, the synthesis and preparation of a new type of graphene composite material suitable for spin-coating into conductive, transparent, and flexible thin film electrodes in ambient conditions is reported.
Abstract: The synthesis and preparation of a new type of graphene composite material suitable for spin-coating into conductive, transparent, and flexible thin film electrodes in ambient conditions is reported here for the first time. Solution-processible graphene with diameter up to 50 mu m is synthesized by surfactant-assisted exfoliation of graphite oxide and in situ chemical reduction in a large quantity. Spin-coating the mixing solution of surfactant-functionalized graphene and PEDOT:PSS yields the graphene composite electrode (GCE) without the need for high temperature annealing, chemical vapor deposition, or any additional transfer-printing process. The conductivity and transparency of GCE are at the same level as those of an indium tin oxide (ITO) electrode. Importantly, it exhibits high stability (both mechanical and electrical) in bending tests of at least 1000 cycles. The performance of organic light-emitting diodes based on a GCE anode is comparable, if not superior, to that of OLEDs made with an ITO anode.
TL;DR: In this paper, a straightforward roll-to-roll process for fabricating flexible and stretchable superaligned carbon nanotube films as transparent conducting films is demonstrated, which are superior in flexibility and wearability to touch panels based on indium tin oxide (ITO).
Abstract: A straightforward roll-to-roll process for fabricating flexible and stretchable superaligned carbon nanotube films as transparent conducting films is demonstrated. Practical touch panels assembled by using these carbon nanotube conducting films are superior in flexibility and wearability—and comparable in linearity—to touch panels based on indium tin oxide (ITO) films. After suitable laser trimming and deposition of Ni and Au metal, the carbon nanotube film possesses excellent performance with two typical values of sheet resistances and transmittances (208 Ω □ ―1 , 90% and 24 Ω □ ―1 , 83.4%), which are comparable to ITO films and better than the present carbon nanotube conducting films in literature. The results provide a route to produce transparent conducting films more easily, effectively, and cheaply, an important step for realizing industrial-scale applications of carbon nanotubes for transparent conducting films.
TL;DR: In this paper, a simple method was developed using metal grid/conducting polymer hybrid transparent electrode to replace indium tin oxide (ITO) for the fabrication of inverted structure polymer solar cells.
Abstract: A simple method was developed using metal grid/conducting polymer hybrid transparent electrode to replace indium tin oxide (ITO) for the fabrication of inverted structure polymer solar cells. The performance of the devices could be tuned easily by varying the width and separation of the metal grids. By combining the appropriate metal grid geometry with a thin conductive polymer layer, substrates with comparable transparency and sheet resistance to those of ITO could be achieved. Polymer solar cells fabricated using this hybrid electrode show efficiencies as high as ∼3.2%. This method provides a feasible way for fabricating low-cost, large-area organic solar cells.
TL;DR: A nanocable array-on-ITO architecture a promising photoelectrode with excellent photovoltaic properties for solar energy applications and the neutral electrodeposition method can be generally used for plating CdTe on nanostructures made of different materials, which would be of interest in various applications.
Abstract: Vertically aligned ZnO/CdTe core−shell nanocable arrays-on-indium tin oxide (ITO) are fabricated by electrochemical deposition of CdTe on ZnO nanorod arrays in an electrolyte close to neutral pH. By adjusting the total charge quantity applied during deposition, the CdTe shell thickness can be tuned from several tens to hundreds of nanometers. The CdTe shell, which has a zinc-blende structure, is very dense and uniform both radially and along the axial direction of the nanocables, and forms an intact interface with the wurtzite ZnO nanorod core. The absorption of the CdTe shell above its band gap (∼1.5 eV) and the type II band alignment between the CdTe shell and the ZnO core, respectively, demonstrated by absorption and photoluminescence measurements, make a nanocable array-on-ITO architecture a promising photoelectrode with excellent photovoltaic properties for solar energy applications. A photocurrent density of ∼5.9 mA/cm2 has been obtained under visible light illumination of 100 mW cm−2 with zero bias...
TL;DR: In this paper, a nickel metal organic ink precursor is used to fabricate NiO hole transport layers on indium tin oxide anodes, which achieves similar OPV device results reported with NiO films from PLD as well as PEDOT:PSS.
TL;DR: It was found that AuCl(3) doping on graphene can alter the graphene surface wetting properties such that a uniform coating of the hole-transporting layer can be achieved and device success rate can be increased, resulting in improved overall PCE performance of the OPV devices.
Abstract: In this work graphene sheets grown by chemical vapor deposition (CVD) with controlled numbers of layers were used as transparent electrodes in organic photovoltaic (OPV) devices. It was found that for devices with pristine graphene electrodes, the power conversion efficiency (PCE) is comparable to their counterparts with indium tin oxide (ITO) electrodes. Nevertheless, the chances for failure in OPVs with pristine graphene electrodes are higher than for those with ITO electrodes, due to the surface wetting challenge between the hole-transporting layer and the graphene electrodes. Various alternative routes were investigated and it was found that AuCl3 doping on graphene can alter the graphene surface wetting properties such that a uniform coating of the hole-transporting layer can be achieved and device success rate can be increased. Furthermore, the doping both improves the conductivity and shifts the work function of the graphene electrode, resulting in improved overall PCE performance of the OPV devices. This work brings us one step further toward the future use of graphene transparent electrodes as a replacement for ITO. (Some figures in this article are in colour only in the electronic version)
TL;DR: It is shown that structural relaxation and densification by In(3+) and Sn(4+) mixing is effective in reducing carrier trap sites and in creating carrier-generating oxygen vacancies.
Abstract: Films of the high-performance solution-processed amorphous oxide semiconductor a-ZnIn4Sn4O15, grown from 2-methoxyethanol/ethanolamine solutions, were used to fabricate thin-film transistors (TFTs) in combination with an organic self-assembled nanodielectric as the gate insulator. This structurally dense-packed semiconductor composition with minimal Zn2+ incorporation strongly suppresses transistor off-currents without significant mobility degradation, and affords field-effect electron mobilities of ∼90 cm2 V−1 s−1 (104 cm2 V−1 s−1 maximum obtained for patterned ZITO films), with Ion/Ioff ratio ∼105, a subthreshhold swing of ∼0.2 V/dec, and operating voltage <2 V for patterned devices with W/L = 50. The microstructural and electronic properties of ZITO semiconductor film compositions in the range Zn9−2xInxSnxO9+1.5x (x = 1−4) and ZnIn8−xSnxO13+0.5x (x = 1−7) were systematically investigated to elucidate those factors which yield optimum mobility, Ion/Ioff, and threshold voltage parameters. It is shown tha...
TL;DR: In this article, the authors compared the impact of the thickness of indium tin oxide (ITO) coated optical fibers on surface plasmon resonances and lossy mode resonances.
Abstract: Surface plasmon resonances and lossy mode resonances (LMRs) can be generated with indium tin oxide (ITO) coated optical fibers. Both phenomena are analyzed and compared. LMRs present important advantages: they do not require a specific polarization of light, it is possible to generate multiple attenuation bands in the transmission spectrum, and the sensitivity of the device to external parameters can be tuned. The key parameter is the thickness of the ITO coating. The study is supported with both theoretical and experimental results. The main purposes are sensing and generation of multiple-wavelength filters.
TL;DR: In this article, a poly-(3-hexylthiophene) (P3HT) nanorods oriented perpendicularly to indium tin oxide (ITO) glass are fabricated using an anodic aluminum oxide template.
Abstract: A structured polymer solar cell architecture featuring a large interface between donor and acceptor with connecting paths to the respective electrodes is explored. To this end, poly-(3-hexylthiophene) (P3HT) nanorods oriented perpendicularly to indium tin oxide (ITO) glass are fabricated using an anodic aluminum oxide template. It is found that the P3HT chains in bulk films or nanorods are oriented differently; perpendicular or parallel to the ITO substrate, respectively. Such chain alignment of the P3HT nanorods enhanced the electrical conductivity up to tenfold compared with planar P3HT films. Furthermore, the donor/acceptor contact area could be maximised using P3HT nanorods as donor and C60 as acceptor. In a photovoltaic device employing this structure, remarkable photoluminescence quenching (88%) and a seven-fold efficiency increase (relative to a device with a planar bilayer) are achieved.
TL;DR: The photoelectrochemical biosensing platform constructed using porphyrin-functionalized TiO₂ nanoparticles had an excellent specificity against anticancer drugs and could be successfully applied to the detection of reduced glutathione in gluthion injection, showing a promising application in photoelectronic biosensing.
Abstract: A novel photoelectrochemical biosensing platform for the detection of biomolecules at relatively low applied potentials was constructed using porphyrin-functionalized TiO₂ nanoparticles. The functional TiO₂ nanoparticles were prepared by dentate binding of TiO₂ with sulfonic groups of water-soluble [meso-tetrakis(4-sulfonatophenyl)porphyrin] iron(III) monochloride (FeTPPS) and characterized by transmission electron microscopy; contact angle measurement; and Raman, X-ray photoelectron, and ultraviolet-visible absorption spectroscopies. The functional nanoparticles showed good dispersion in water and on indium tin oxide (ITO) surface. The resulting FeTPPS-TiO₂-modified ITO electrode showed a photocurrent response at +0.2 V to a light excitation at 380 nm, which could be further sensitized through an oxidation process of biomolecules by the hole-injected FeTPPS. Using glutathione as a model, a methodology for sensitive photoelectrochemical biosensing at low potential was thus developed. Under optimal conditions, the proposed photoelectrochemical method could detect glutathione ranging from 0.05 to 2.4 mmol L⁻¹ with a detection limit of 0.03 mmol L⁻¹ at a signal-to-noise ratio of 3. The photoelectrochemical biosensor had an excellent specificity against anticancer drugs and could be successfully applied to the detection of reduced glutathione in gluthion injection, showing a promising application in photoelectrochemical biosensing.
TL;DR: In this article, the nano-composite films of expandable graphene sheet (Pt/EGS) are fabricated on conductive indium tin oxide glass electrodes via a green electrochemical synthetic route involving a series of electrochemical processes.
TL;DR: In this paper, the authors used spinach extract, ipomoea leaf extract and their mixed extracts as the natural dyes for a dye-sensitized solar cell (DSSC).
TL;DR: In this article, the conductivity enhancement of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films through a treatment with aqueous solutions of zwitterions for the first time was reported.
Abstract: This paper reports the significant conductivity enhancement of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films through a treatment with aqueous solutions of zwitterions for the first time. The conductivity enhancement was dependent on the structure of the zwitterions and the experimental conditions during the treatment, such as the concentration of the zwitterions and the temperature. Conductivity enhancement from 0.2 to 92.4 S cm−1 was observed on PEDOT:PSS films after a zwitterion treatment. The chemical and physical characterizations indicate the lowering of the energy barrier for charge hopping across the PEDOT chains, the loss of poly(styrene sulfonate) acid (PSSH) chains from the PEDOT:PSS film, and the conformational change of the PEDOT chains after the zwitterion treatment. These highly conductive PEDOT:PSS films could be used to replace indium tin oxide (ITO) as the transparent anode of polymer photovoltaic cells (PVs). Power conversion efficiency as high as 2.48% was observed on the polymer PVs with a zwitterion-treated PEDOT:PSS film as the transparent anode.
TL;DR: In this article, the effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells are investigated using poly(3,4-ethylenedioxythiophene) : p o l y(st y rene sulfonate) (PEDOT:PSS) and/or a holetransporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi 2
Abstract: The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene) : p o l y(st y rene sulfonate) (PEDOT:PSS) and/or a holetransporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi 2 ) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi 2 :TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V oc ), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi 2 :TFB together in the same cell greatly reduces dark current and produces the highest V oc (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and solvent cleaning markedly affect cell response in combination with each IFL. O 2 plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi 2 :TFB IFL. Solvent cleaning leaves significant residual carbon contamination on the ITO and is best followed by O 2 plasma or UV ozone treatment.
TL;DR: In this paper, the influence of solution-processed molybdenum oxide (MoO3) as an anode buffer layer on the device performance of P3HT:PCBM PV cells is investigated as compared to the PV cells with different anode buffers, including water-soluble poly(ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and the thermally evaporated MoO3.
TL;DR: In this paper, hierarchical dendritic gold microstrutures (HDGMs) with secondary and tertiary branches are directly electrodeposited on an indium tin oxide (ITO) substrate without the use of any templates, surfactants, or stabilizers.
Abstract: Hierarchical dendritic gold microstrutures (HDGMs) with secondary and tertiary branches are directly electrodeposited on an indium tin oxide (ITO) substrate without the use of any templates, surfactants, or stabilizers. The effects of electrodeposition potential and HAuCl4 concentration on the formation of HDGMs and time-dependent morphological evolution are investigated in detail. A diffusion-limited aggregation (DLA) mechanism is used to explain the formation of HDGMs. Typically, the as-synthesized HDGMs exhibited much higher electrocatalytic activity and enhanced stability toward ethanol electrooxidation compared to bulk gold electrode and also display great Raman enhancement activity with the detection limit of 10−12 M for rhodamine 6G. The surface of HDGMs possesses hydrophobicity even without modification with low-surface-energy coatings and has a remarkable superhydrophobic property even in corrosive solutions over a wide pH range after the treatment with n-dodecanethiol. In addition, (super)oleoph...
TL;DR: In this article, the reduced graphene oxide (rGO) films, ZnO nanorods, as well as p-type and n-type Cu2O films with good crystallinity have been electrochemically deposited and then characterized.
Abstract: Flexible, transparent, and conductive electrodes are prepared by reduction of the graphene oxide (GO) films which were spin-coated on the polyethylene terephthalate (PET) substrates. On the reduced graphene oxide (rGO) films, ZnO nanorods, as well as p-type and n-type Cu2O films with good crystallinity have been electrochemically deposited and then characterized. Meanwhile, the effect of pH value of the deposition bath on the morphology, structure, and semiconducting property of the electrochemical deposited Cu2O has been studied. Our results provide a possible way to replace the indium tin oxide (ITO) and fluorine tin oxide (FTO) electrodes with rGO films in the electrochemical synthesis, and make it promising to synthesize semiconductor oxides on rGO films for future flexible photovoltaic applications.
TL;DR: A novel anode structure based on micropatterned ITOs coated with high-conductivity (HC)-grade poly(3,4ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) layers is introduced to improve the outcoupling efficiency of OLEDs in a relatively simple way.
Abstract: Organic light-emitting diodes (OLEDs) are now entering mainstream display markets and are also being explored for next-generation lighting applications. In both types of applications, high external quantum efficiency (EQE) is of premium importance for both low power consumption and long lifetime. It is well known that one of the bottlenecks in achieving high EQE in OLEDs is the low light-extraction efficiency, which is limited to <20%, mostly because total internal reflections occurring at interfaces between optically distinctive layers confine a significant portion of the light within the substrate (1⁄4 ‘‘substrate-confined’’ mode) or within the organic/indium tin oxide (ITO) layers (1⁄4 ‘‘wave-guided’’ mode). Hence, many device structures have been proposed to extract light that would not normally be outcoupled: some have attempted to extract the light that is confined in a substrate by introducing structures such as microlens array (MLA) or pyramidal arrays on the backside of the substrate, where other research groups have tried to extract the light that is confined within organic/ITO layers by introducing optical structures such as photonic crystals or low-index grids that can disrupt the wave-guiding of the light within the organic/ITO layers. The lattermay be carried out in a direct way by converting wave-guided modes directly into outcoupled modes or in an indirect way by converting wave-guided modes into substrate-confined modes and then extracting them with structures mentioned in the former approach. Criteria for choosing a specific method or structure over others depend on the target applications: for display applications, methodologies such as MLA and substrate structuring are often avoided due to their optical blurring effect; for lighting applications, such methods are readily accepted, but complex processes that add too much cost are generally not welcomed. In both cases, compatibility with a common fabrication technique and large-area fabrication is strongly preferred, and the Lambertian angular dependence and the absence of spectral dependence are also preferred in most situations. Here we introduce a novel anode structure based on micropatterned ITOs coated with high-conductivity (HC)-grade poly(3,4ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) layers. This proposed electrode structure can improve the outcoupling efficiency of OLEDs in a relatively simple way without severe spectral dependence, blurring (optional), or deviation from the normal angular dependence. Figure 1 illustrates a tilted top-view and cross-section of the proposed anode structure and its working principle. ITO layers are patterned so that the square opening (Wo Wo) repeats in a square lattice layout with a spatial period ofWt. For simplicity, we consider a situation where Wt1⁄4 2 Wo. In this case, the width of ITO strips (WITO (1⁄4Wt–Wo)) next to each opening equalsWo, and the ITO-less portion is 25% per each unit cell. The spatial period and the dimension of openings are chosen to be sufficiently larger than the emission wavelength so that a geometric optic approach can be valid and spectral dependence may be ignored. Each pattern may have a taper angle utaper, as defined in Figure 1a. A high-conductivity PEDOT:PSS (Baytron PH 500, HC Starck, Inc.) layer is coated throughout the anode area over the patterned anode. Organic layers and metal cathodes are then deposited to complete the device. Note that the light emitted with a small angle within the emission layer, which would normally be wave-guided throughout the organic/ ITO layers, is now guided either solely within organic layers (the ray in red coming from the left side in Figure 1b) or solely within ITO layers (the ray in blue coming from the right side in Figure 1b), because the refractive index ( 1.42 at l1⁄4 550 nm) of PEDOT:PSS is lower than those of ITOs and typical organic layers used in OLEDs. Upon hitting the structured region once or multiple times, the guided light will change its direction so that it can be directly coupled out. Some portion of the wave-guided mode can also be converted to a substrate-confined mode (see Figure S1 in Supporting Information). It has to be noted that patterned ITO electrodes alone without the PEDOT:PSS overcoat would not work effectively, because organic layers and ITO layers are optically almost identical due to their similar refractive indices. The low refractive index of a PEDOT:PSS layer is indeed the characteristic that enables internal reflections at the structured interfaces, which are among the key processes that must occur in order for the guided light to be converted to an outcoupled or a substrate-confined mode. In addition to the optical benefits noted above, it is also critical that, in the region without ITO, the HC-grade PEDOT:PSS layer provides an electrical sheet conduction and works as an anode independently so that there is no inactive area in the devices. In fact, we note each anode region consisting solely of PEDOT:PSS is surrounded by ITO electrodes, resembling the conductive grid structure suggested by Leo and his coworkers that can ensure
TL;DR: In this paper, a thin-film organic electroluminescence diode was fabricated, which consists of an indium tin oxide (ITO) anode, a Au nanoparticle array, a Cu phthalocyanine hole transport layer, a tris(8-hydroxylquinolianato) aluminum (III) electron transport layer and a LiF electron injection layer.
Abstract: A significant increase in electroluminescence was achieved through coupling with localized surface plasmons in a single layer of Au nanoparticles. We fabricated a thin-film organic electroluminescence diode, which consists of an indium tin oxide (ITO) anode, a Au nanoparticle array, a Cu phthalocyanine hole transport layer, a tris(8-hydroxylquinolianato) aluminum (III) electron transport layer, a LiF electron injection layer, and an Al cathode. The device structure, with size-controlled Au particles embedded on ITO, can be used to realize the optimum distance for exciton-plasmon interactions by simply adjusting the thickness of the hole transport layer. We observed a 20-fold increase in the molecular fluorescence compared with that of a conventional diode structure.
TL;DR: The role of ITO and PEDOT:PSS on the current-tension characteristics, on open circuit voltage Voc, and on density of short-circuit current Jsc was investigated for the two polymers:PCBM blend solar cells as deposited and after 40 days ageing as mentioned in this paper.