Commercial Indium Tin Oxide Research Articles

An ultra-sensitive bimetallic based electrochemical sensor for analysis of total iron, total dissolved iron, and granular iron in coastal water

Different iron species play crucial roles in the biogeochemical cycle, so their determination is important. Electrochemical methods are among the most promising and easiest methods for the rapid on-site determination of different iron species. In this study, a new electrode—Au–Bi/ITO—based on the commercial indium tin oxide (ITO) electrode was etched and functionalized with bismuth nanoparticles (BiNPs) and gold nanoparticles (AuNPs) nanocomposites for voltammetric analysis of iron species in coastal water. After etching, the ITO electrode exhibits a higher number of attachment sites for the nanomaterials, thereby improving the stability of the resulting electrode, and the introduction of the nanomaterials improves the sensitivity of the electrode, making it easier to realize on-site detection. Under the synergistic effect of the two nanomaterials, the Au-Bi/ITO electrode showed excellent performance for the determination of different iron species in coastal water. Under the optimal conditions, the Au-Bi/ITO electrode peak current was linear in the concentration range from 5 nM to 1.5 μM with an ultralow detection limit of 1.4 nM. The results are consistent with certified values when the electrode is used for the determination of Fe(III) in certified reference materials. In summary, the Au-Bi/ITO electrode, with its high stability and sensitivity, has been successfully used for the direct determination of different Fe(III) species in coastal water via cathodic stripping voltammetry. This electrode is simple to prepare, easy to use, economical, and highly promising for future applications involving the rapid on-site detection of different iron species.

Over-Time Stability Evaluation of Fluorinated Self-Assembled Monolayer on Commercial Indium Tin Oxide Electrode on PET Substrate

Motivation: Self-Assembled Monolayer (SAM) modified electrode has a key role in electrochemical biosensor applications to achieve desired sensing properties such as selective interaction with target protein and anti-fouling properties of non-specific protein. However, the degradation of SAM layer on the electrode can cause the electrochemical response to drift over time. This causes adversary effect on the designed biosensor such as limited shelf life and inconsistent electrochemical signal reading between electrodes. For that matter, it is important to understand the signal drift behaviour and ultimately obtain a SAM-modified electrode with good stability over time. In this study, we observed the signal drift of SAM-modified indium tin oxide electrode on PET substrate (ITO-PET). Three-electrode electrochemical impedance spectroscopy (EIS) measurement was carried to evaluate the electrochemical properties of the ITO-PET substrate over time. Materials and Methods: Commercial ITO-PET (Adafruit, NY, USA) was used as electrode and was modified using Perfluoro-octyltriethoxysilane (Sigma Aldrich, St. Louis, MO, USA) self-assembled monolayer. The ITO-PET substrate was modified by using room temperature RCA-1 silanization process as shown in Figure 1. The modified electrode was rinsed in ethanol and DI water and stored in dark condition with temperature of 5oC. The Electrochemical Impedance Spectroscopy measurements were carried by using Solartron SI1260 impedance analyser tandem with SI1287 potentiostat. with saturated KCl Ag/AgCl (RRPEAGCL2, Pine Research, NC, USA) electrode and Pt wire counter electrode (MW-1032; BASi, West Lafayette, IN, USA). Potassium Ferricyanide (K3Fe(CN)6) (Fischer Scientific, Fair Lawn, NJ, USA) with concentration of 10 mM in 1x PBS was used as redox probe. The EIS run was set at 0.31 Vdc and 10 mV Vac amplitude with frequency ranging from 0.1 – 10000 Hz. Results: We observed significant increase charge transfer resistance (Rct)increase of SAM-ITO sample (4498 ± 460 Ω.cm2) compared to the bare ITO sample (1348 ± 68 Ω.cm2). The signal also maintains its consistency after one week of storage in enclosed dry and dark environment at 5oC with 3% change in average Rct value (133 Ω.cm2). Ongoing work in this study includes the electrochemical signal evaluation of the ITO-SAM electrode exposed to protein such as casein and BSA. Figure 1

Incoherent partial superposition modeling for single-shot angle-resolved ellipsometry measurement of thin films on transparent substrates

Ellipsometric measurement of transparent samples suffers from substrate backside reflection challenges, including incoherent and partial superposition issues. The recently developed angle-resolved ellipsometry (ARE) can naturally eliminate the backside reflections of substrates with a micro-spot equivalent thickness or thicker; however, for thinner substrates, ARE working with general incoherent backside reflection models shows significant inaccuracy or measurement failure. In this paper, an incoherent partial superposition (IPS) model is proposed to characterize the optical superposition effect between the frontside and uncertain backside reflections from an unknown substrate. IPS introduces a cosine-like correction of the backside reflection, corresponding to the overlapping-area change of backside and frontside reflections along with incident angles. Benefiting from ARE’s wide-angle spectral imaging capability, IPS achieves single-shot measurement of thin film thicknesses on transparent substrates of unknown thickness. An ARE system was built and calibrated regarding the linear relationship between the cosine-corrected angular frequencies and substrate thicknesses. Then, commercial ITO films on glasses of different thicknesses ranging from 200 to 1000 µm were measured. Experimental results show that IPS-ARE results in a root-mean-square accuracy error of ∼1 nm in film thickness measurement and provides a ∼77% error reduction from general incoherent backside reflection models.

High-Resolution Printing of Various Electronic Materials by Electrophotography

Electrophotography is a digital, on-demand, dry, and page printing technique that operates based on toner particles of electronic materials using an electrostatic force and generates an electrical circuit via distribution of the toner particles. We developed a 10 μm linewidth resolution with various electronic materials, including conductors, semiconductors, and insulators, without any chemical pretreatments on the substrate films, while a 5 μm resolution was also possible for limited materials. The electrical resistivity of the printed Ag–Ni after an intense pulse light sintering was comparable to that of commercial indium tin oxide transparent films.

Ga, Mg, F ternary-doped ZnO-based transparent conductive film prepared by radio-frequency sputtering with high transmittance

Ga/Mg/F ternary-doped ZnO transparent conductive films were prepared by radio-frequency (RF) magnetron sputtering. The influences of RF power, work pressure, and substrate temperature on the films are studied. The electrical and optical properties, structure and surface morphology of the films are discussed. Compared to other doped systems, the deposited films in this work exhibit excellent electrical and optical properties (ρ: 4.79 × 10−4 Ω·cm, T: 91.4%), which is comparable to commercial ITO. Besides, the films with the best performance show good stability. Our work has verified the advantages of triple-doped ZnO transparent conductive films, which is meaningful for future research and applications.

Metal nanowire-based transparent electrode for flexible and stretchable optoelectronic devices.

High-quality transparent electrodes are indispensable components of flexible optoelectronic devices as they guarantee sufficient light transparency and electrical conductivity. Compared to commercial indium tin oxide, metal nanowires are considered ideal candidates as flexible transparent electrodes (FTEs) owing to their superior optoelectronic properties, excellent mechanical flexibility, solution treatability, and higher compatibility with semiconductors. However, certain key challenges associated with material preparation and device fabrication remain for the practical application of metal nanowire-based electrodes. In this review, we discuss state-of-the-art solution-processed metal nanowire-based FTEs and their applications in flexible and stretchable optoelectronic devices. Specifically, the important properties of FTEs and a cost-benefit analysis of existing technologies are introduced, followed by a summary of the synthesis strategy, key properties, and fabrication technologies of the nanowires. Subsequently, we explore the applications of metal-nanowire-based FTEs in different optoelectronic devices including solar cells, photodetectors, and light-emitting diodes. Finally, the current status, future challenges, and emerging strategies in this field are presented.

Photo-bioelectrochemical cell anodes enhanced with titanium oxide, carbon nanotubes and chlorophyll-based catalyst on different supporting materials

An important part of a photo-bioelectrochemical cell (PBEC) is the photo-biocatalyst substrate taken as anode. This study aims to explain the effect of CNT/TiO2/chlorophyll photocatalyst coated on the cellulose nanopaper (CNP) substrate on the PBEC performance and to compare the results with those obtained for the commercial indium tin oxide (ITO) glass and flexible ITO as substrates. The results showed high sheet resistance of CNP, which is 61182 Ω sq-1, which is reduced by 80 % in the presence of CNT/TiO2/Chl biocatalyst. The highest output voltage of 0.95 to 1 V was produced by coating CNT/TiO2/Chl on the flexible ITO. The maximum current density (Jmax) of 3726 mA m-2 and the highest maximum power density value of around 574 mW m-2 were obtained for illuminated CNT/TiO2/Chl on the rigid ITO anode. In dark conditions, the highest power density was observed for CNP as the supporting substrate. The photo-bioelectrochemical cell adopting CNT/TiO2/Chl and CNP as the supporting substrate material has great potential for a variety of applications, such as wearable electronics, environmental monitoring, remote or off-grid energy supply, and renewable energy systems, thereby contributing to the advancement of sustainable energy technologies.

Sn Composition Engineering Toward the Breakthrough of Transparent Front Electrodes for Efficient and Stable Perovskite Solar Cells

AbstractTo overcome the Shockley–Queisser limit, studies have focused on improving the efficiency of perovskite solar cells (PSCs) through several optimization and tandem‐structure design strategies. Furthermore, the significance of emerging transparent front electrodes (TFEs), which exert a direct and substantial influence on the performance of PSCs, is on the rise. Therefore, further research must be conducted to validate these effects in improving the existing performance of PSCs. Thus, this study developed a composition‐engineered indium tin oxide (CE‐ITO) TFE that outperforms commercial ITO (C‐ITO; 10 at.% Sn doped ITO) for efficient and stable PSCs. The CE‐ITO electrode (7.50 at.% Sn doped ITO) has a large columnar structure and good thermal stability, which are ideal for high‐performance PSCs. Compared to C‐ITO, CE‐ITO has a smoother surface, higher conductivity, lower resistivity, and improved optical transmittance in the active layer. These contribute to the larger perovskite active‐ and electron‐transport layers, less active‐layer degradation, and lower shunt resistance. The various merits of CE‐ITO enable high‐performance PSCs with a maximum power conversion efficiency of 23.35% and long‐term stability by simply substituting C‐ITO with optimal CE‐ITO.

Breaking through the plasma wavelength barrier to extend the transparency range of ultrathin indium tin oxide films into the far infrared

Indium tin oxide (ITO) film, which is the most commonly used transparent conductive film (TCF), has traditionally been believed to be transparent in the visible spectrum but to reflect infrared (IR) light beyond the plasma wavelength (λp). However, our theoretical analysis challenges this notion by demonstrating that an ultrathin ITO TCF that is thinner than the light's penetration depth can overcome the transmission barrier at λp. To validate the theoretical modeling, we have successfully fabricated ultrathin ITO films that, despite having λp ≈ 1 μm, remain transparent from 400 nm to 20 μm. This represents the broadest transparency range ever reported for any In2O3-based TCF. The 10-nm-thick ITO TCFs have high visible transmittance (91.0% at 550 nm), low resistivity (5 × 10−4 Ω cm), and good IR transmittance (averaging 60% over 1.35–18.35 μm). Their IR transparency facilitates radiative cooling of the underlying circuitry. When an operational resistor is enclosed by commercial ITO TCFs that are 140 nm thick, its temperature increases. However, using 10-nm-thick ITO TCFs instead of the commercial ones can completely avoid this temperature rise. Moreover, attaching a silver grid to a 10-nm-thick ITO TCF can reduce the effective sheet resistance to ∼10 Ω/□ at the expense of only ∼3% transmittance. This development paves the way for large-scale applications that require low sheet resistance and far-IR transparency.

Effects of Post-Annealing on the Properties of ZnO:Ga Films with High Transparency (94%) and Low Sheet Resistance (29 Ω/square).

This study presents gallium-doped zinc oxide (ZnO:Ga, GZO) thin films. GZO thin films with both high transparency and low sheet resistance were prepared by RF sputtering and then post-annealed under nitrogen and hydrogen forming gas. With post-annealing at 450 °C, the proposed films with a film thickness of 100 nm showed high transparency (94%), while the sheet resistance of the films was reduced to 29 Ω/square, which was comparable with the performances of commercial indium tin oxide (ITO) samples. Post-annealing under nitrogen and hydrogen forming gas enhanced the films' conductivity while altering the thin-film composition and crystallinity. Nitrogen gas played a role in improving the crystallinity while maintaining the oxygen vacancy of the proposed films, whereas hydrogen did not dope into the thin film, thus maintaining its transparency. Furthermore, hydrogen lowered the resistance of GZO thin films during the annealing process. Then, the detailed mechanisms were discussed. Hydrogen post-annealing helped in the removal of oxygen, therefore increasing the Ga3+ content, which provided extra electrons to lower the resistivity of the films. After the preferable nitrogen/hydrogen forming gas treatment, our proposed films maintained high transparency and low sheet resistance, thus being highly useful for further opto-electronic applications.

Stability enhancement of silver nanowire-based flexible transparent electrodes for organic solar cells

Flexible organic solar cells (OSCs) are one of the most promising power sources for wearable electronics. A high-quality transparent electrode is one of the indispensable components for OSCs because it guarantees sufficient light transparency and electrical conductivity. Silver nanowires (AgNWs) are considered to be an ideal candidate over commercial rigid indium tin oxide as flexible transparent electrodes (FTEs) because of their superior optoelectronic properties, excellent mechanical flexibility, solution treatability, and high compatibility with semiconductors. However, the stability of AgNWs-based FTEs (AgNWs-FTEs) hinders their further application. In this perspective, we provide state-of-the-art solution-processed AgNWs with enhanced stability and their applications in flexible OSCs. We start with a systematic analysis of the failure mechanisms and evaluation methods of AgNWs-FTEs. Then the key reinforced materials are summarized. Next, the main stability enhancement strategies are briefly discussed. Applications of AgNWs-FTEs in flexible and stretchable OSCs are further surveyed. Finally, an outlook on the current status, future challenges, and emerging strategies in this field is presented.

Highly Efficient HTM-Free Tin Perovskite Solar Cells with Outstanding Stability Exceeding 10000 h.

The bottleneck in the rapid development of tin-based perovskite solar cells (TPSCs) is the inherent chemical instability. Although this is being addressed continuously, the device performance has not improved further due to the use of PEDOT:PSS as the hole-transport material (HTM), which has poor long-term stability. Herein we have applied commercial ITO nanoparticles over ITO glass substrates and altered the surface chemistry of the ITO electrode via a simple two-step thermal annealing, followed by a UV-ozone treatment. These surface-modified ITO electrodes display promising interfacial characteristics, such as a suitable band alignment owing to significantly reduced surface carbon contamination, increased In-O bonding, and reduced oxygen vacancies, that enabled fabrication of an HTM-free TPSC device according to a two-step method. The fabricated device possessed an outstanding power conversion efficiency (PCE) of 9.7%, along with a superior long-term stability by retaining over 90% of the initial PCE upon shelf storage in a glovebox for a period of over 10000 h. The application of ITO nanoparticles led to effective interfacial passivation, whose impacts on the long-term durability were assessed using electrochemical impedance spectroscopy, time-resolved photoluminescence decay profiles, and femtosecond transient absorption spectroscopy techniques.

Visible and infrared transparent conductive films with passive cooling capabilities

In order to facilitate radiative cooling in optoelectronic devices, it is necessary to employ infrared (IR) transparent conductive films (TCFs) that permit thermal radiation from internal circuits to pass through. This can be accomplished by using TCFs with a wide transparency range that extends into the far-IR spectrum. We have produced hafnium-doped indium oxide (InHfO) TCFs that have a wide transparency range spanning from 400 nm to 20 μm. These TCFs, with a thickness of 120 nm, exhibit a sheet resistance of approximately 200 Ω/□, high visible relative transmittance (90% at 550 nm, comparable to ITO), and IR transparency (66.9% in the 1.35–20 μm range). By replacing commercial ITO TCFs with InHfO TCFs, we successfully decreased the operating temperature of an enclosed resistor from 65.5 °C to 63.6 °C, and potentially to 61.1 °C via radiative cooling. This decrease corresponds to around 5–10% of the temperature difference between the resistor and room temperature. The InHfO TCFs we have prepared are suitable for a range of applications requiring transparency from the visible to the far-IR spectrum and may open up new avenues for optoelectronic applications.

High optoelectronic quality of AZO films grown by RF-magnetron sputtering for organic electronics applications

Aluminum-doped zinc oxide thin films, known by the acronym AZO, were grown by radio-frequency magnetron sputtering method (rf-magnetron sputtering) onto glass substrate at room temperature and without posterior heat treatment. The impact on the structural, electrical, and optical properties of the AZO films was studied as a function of the following deposition parameters: working pressure, rf-power and thickness. Our films showed low electrical resistivity and high transmittance in the visible region comparable to commercial indium tin oxide (ITO) films. We obtained an optimized AZO film with an electrical resistivity of 4.90 × 10−4 Ωcm and presented optical transmittance strikingly high for such a good conductor, with about 98% at 580 nm and an average optical transmittance of about 92% in the visible region. We also built and characterized an organic light-emitting diode (OLED) using the optimized AZO film as a transparent electrode. The AZO-based OLED showed characteristics comparable to a reference ITO-based device, indicating that AZO films have optoelectronic properties good enough to be used in organic electronics. In addition, the results suggest that they are suitable to be employed as transparent conductors in flexible polymeric substrates since their synthesis was performed without intentional heating.

Fabrication and processing of bacterial cellulose/silver nanowire composites as transparent, conductive, and flexible films for optoelectronic applications

AbstractThis work reports on the engineering and fabrication of transparent, conductive, and flexible films made as a composite of bacterial cellulose microfibers (BMF), a polymer (either PVA or PEO), and silver nanowires (AgNWs) as viable and cost‐effective replacements to commercial indium‐tin oxide (ITO) and fluorine‐doped tin oxide (FTO) transparent conductors. The studies conducted indicate that the optical and mechanical properties of BMF‐polymer substrates are tuneable by varying the ratio of BMF to polymer. An optimized ratio of 70:30 of BMF to polymer was established for BMF‐PVA and BMF‐PEO composites. The optimized composite films were coated with varying amounts of AgNWs. As the AgNW loading increased, the deposition density of AgNW networks increased, while the sheet resistance and optical transmittance decreased. The optimum AgNW loading was determined at 0.20 mg for both composite films. The BMF‐PVA‐AgNW film displayed transmittance between 81% and 71% and an average resistivity of 9.462 ± 0.588 Ω/sq while the BMF‐PEO‐AgNW films showed transmittance between 73% and 65% and an average resistivity of 9.388 ± 0.1.375 Ω/sq. These properties compared well to that of commercial ITO and FTO glass substrates. The findings promote cellulose‐based composites as low‐cost, lightweight, and durable substrates for optoelectronic applications.

High Performance Transparent Silver Grid Electrodes for Organic Photovoltaics Fabricated by Selective Metal Condensation.

We report silver grid electrodes on glass and flexible plastic substrates with performance that exceeds that of commercial indium-tin oxide (ITO) coated glass and show their suitability as a drop-in replacement for ITO glass in solution processed organic photovoltaics (OPVs). When supported on flexible plastic substrates these electrodes are stable towards repeated bending through a small radius of curvature over tens of thousands of cycles. The grid electrodes are fabricated by the unconventional approach of condensation coefficient modulation using a perfluorinated polymer shown to be far superior to the other compounds used for this purpose to date. The very narrow line-width and small grid pitch that can be achieved also opens the door to the possibility of using grid electrodes in OPVs without a conducting PEDOT:PSS layer to span the gaps between grid-lines. This article is protected by copyright. All rights reserved.

Ionic Liquid-Assisted Ink for Inkjet-Printed Indium Tin Oxide Transparent and Conductive Thin Films

Drop-on-demand inkjet printing is used to deposit indium tin oxide (ITO) transparent and conductive thin films. ITO printable ink is prepared by dissolving indium hydroxide and tin (IV) chloride into ethanol with the assistance of acetic acid/tert-butylamine ionic liquid. Ionic liquid-assisted ITO ink exhibits a complete wetting behavior on the glass substrate and a tunable viscosity, which makes it particularly suitable for the inkjet printing fabrication of ITO thin films. After annealing at 500 °C in forming gas, ITO thin films with a sheet resistance of 99 Ω/□, a resistivity of 2.28 × 10-3 Ω·cm, and a transmittance of 95.2% in the range of 400-1000 nm can be obtained. The effects of annealing temperature on the resistivity, mobility, carrier concentration, transmittance, and optical band gap are investigated systematically. Compared with commercial ITO thin films made by conventional vacuum-based deposition approaches, these printable ITO thin films have a higher material utilization.

Investigation of the Optical Properties of Indium Tin Oxide Thin Films by Double Integration Sphere Combined with the Numerical IAD Method.

Transparent conductive electrodes have become essential components of numerous optoelectronic devices. However, their optical properties are typically characterized by the direct transmittance achieved by making use of spectrophotometers, avoiding an in-depth knowledge of the processes involved in radiation attenuation. A different procedure based on the Double Integration Sphere combined with the numerical Inverse Adding-Doubling (IAD) method is employed in this work to provide a comprehensive description of the physical processes limiting the light transmittance in commercial indium tin oxide (ITO) deposited on flexible PET samples, highlighting the noticeable contribution of light scattering on the total extinction of radiation. Moreover, harnessing their flexibility, the samples were subjected to different mechanical stresses to assess their impact on the material's optical and electrical properties.

All solution prepared WOx/AgNW composite transparent conductive films with enhanced adhesion and stability

Novel transparent composite conductor composed of WOx/Ag nanowire (NW) on a flexible polyethylene terephthalate (PET) substrate with enhanced adhesion and stability, is prepared by all solution process. The WOx/Ag NW films exhibit low sheet resistance of 9.4 Ω/sq. and high optical transmittance of 82.6 %, these are superior to that of commercial ITO films on PET substrates. Meanwhile, the sheet resistance does not show great change after bending and taping tests, indicating a good flexibility and adhesion of AgNW to the PET. Moreover, WOx/AgNW thin films show a good stability to resist high temperature, high humidity and strong oxidation environment.

Al-Doped ZnO Thin Films with 80% Average Transmittance and 32 Ohms per Square Sheet Resistance: A Genuine Alternative to Commercial High-Performance Indium Tin Oxide

In this study, a low-sophistication low-cost spray pyrolysis system built by undergraduate students is used to grow aluminum-doped zinc oxide thin films (ZnO:Al). The pyrolysis system was able to grow polycrystalline ZnO:Al with a hexagonal wurtzite structure preferentially oriented on the c-axis, corresponding to a hexagonal wurtzite structure, and exceptional reproducibility. The ZnO:Al films were studied as transparent conductive oxides (TCOs). Our best ZnO:Al TCO are found to exhibit an 80% average transmittance in the visible range of the electromagnetic spectrum, a sheet resistance of 32 Ω/□, and an optical bandgap of 3.38 eV. After an extensive optical and nanostructural characterization, we determined that the TCOs used are only 4% less efficient than the best ZnO:Al TCOs reported in the literature. This latter, without neglecting that literature-ZnO:Al TCOs, have been grown by sophisticated deposition techniques such as magnetron sputtering. Consequently, we estimate that our ZnO:Al TCOs can be considered an authentic alternative to high-performance aluminum-doped zinc oxide or indium tin oxide TCOs grown through more sophisticated equipment.