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S. Kiruthika

Other affiliations: Bharathidasan University
Bio: S. Kiruthika is an academic researcher from Jawaharlal Nehru Centre for Advanced Scientific Research. The author has contributed to research in topics: Electrode & Materials science. The author has an hindex of 12, co-authored 22 publications receiving 694 citations. Previous affiliations of S. Kiruthika include Bharathidasan University.

Papers
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Journal ArticleDOI
TL;DR: This review provides topical coverage of next generation transparent conducting electrodes (TCE) based on a wide range of materials such as oxide nanoparticles, CNTs, graphene, metal nanowires, metal meshes and their hybrids.
Abstract: Heater plates or sheets that are visibly transparent have many interesting applications in optoelectronic devices such as displays, as well as in defrosting, defogging, gas sensing and point-of-care disposable devices. In recent years, there have been many advances in this area with the advent of next generation transparent conducting electrodes (TCE) based on a wide range of materials such as oxide nanoparticles, CNTs, graphene, metal nanowires, metal meshes and their hybrids. The challenge has been to obtain uniform and stable temperature distribution over large areas, fast heating and cooling rates at low enough input power yet not sacrificing the visible transmittance. This review provides topical coverage of this important research field paying due attention to all the issues mentioned above.

183 citations

Journal ArticleDOI
TL;DR: Spray coating in the context of crack template is a powerful method for producing transparent heaters, which is shown for the first time in this work.
Abstract: Transparent conducting electrodes (TCEs) have been made on flat, flexible, and curved surfaces, following a crack template method in which a desired surface was uniformly spray-coated with a crackle precursor (CP) and metal (Ag) was deposited by vacuum evaporation. An acrylic resin (CP1) and a SiO2 nanoparticle-based dispersion (CP2) derived from commercial products served as CPs to produce U-shaped cracks in highly interconnected networks. The crack width and the density could be controlled by varying the spray conditions, resulting in varying template thicknesses. By depositing Ag in the crack regions of the templates, we have successfully produced Ag wire network TCEs on flat-flexible PET sheets, cylindrical glass tube, flask and lens surface with transmittance up to 86%, sheet resistance below 11 Ω/□ for electrothermal application. When used as a transparent heater by joule heating of the Ag network, AgCP1 and AgCP2 on PET showed high thermal resistance values of 515 and 409 °C cm2/W, respectively, wi...

125 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a four-step process involving deposition of commercially available colloidal dispersions onto polyethylene terephthalate (PET), drying to induce crackle network formation, nucleating Au or Pd seed nanoparticles inside the crackle regions, washing away the sacrificial layer and finally, depositing Cu electrolessly or by electroplating.
Abstract: Virtually unlimited and highly interconnected Cu wire networks have been fabricated on polyethylene terephthalate (PET) substrates with sheet resistance of <5 Ω □−1 and transmittance of ∼75%, as alternatives to the commonly used tin doped indium oxide (ITO) based electrodes. This is a four step process involving deposition of commercially available colloidal dispersions onto PET, drying to induce crackle network formation, nucleating Au or Pd seed nanoparticles inside the crackle regions, washing away the sacrificial layer and finally, depositing Cu electrolessly or by electroplating. The formed Cu wire network is continuous and seamless, and devoid of crossbar junctions, a property which brings high stability to the electrode towards oxidation in air even at 130 °C. The flexible property of the PET substrate is easily carried over to the TCE. The sheet resistance remained unaltered even after a thousand bending cycles. The as-prepared Cu wire network TCE is hydrophobic (contact angle, 80°) which, upon UV–ozone treatment, turned to hydrophilic (∼40°).

82 citations

Journal ArticleDOI
TL;DR: In this article, a review deals with a range of materials and processes forming new generation transparent electrodes, while giving some insight into the cost of these materials and their application in optoelectronic or transparent devices.
Abstract: A transparent electrode is a key component of any optoelectronic or transparent device. With increasing number of large area applications, there is growing demand to replace the conventional oxide based transparent conducting films with nanomaterials, primarily to reduce the cost. This review deals with a range of materials and processes forming new generation transparent electrodes, while giving some insight into the cost.

72 citations

Journal ArticleDOI
TL;DR: In this paper, an interconnected Ag mesh was fabricated by depositing metal over the crackle network followed by the removal of the template, which achieved uniform temperatures up to 170 °C on the electrode area and a high thermal resistance of 255.2 °C cm2 W−1.
Abstract: Highly interconnected crackles were obtained by spreading commercially available low cost crackle wall paint based precursor by the drop coating technique. An interconnected Ag mesh was fabricated by depositing metal over the crackle network followed by the removal of the template. The metal network is well conducting (1 Ω □−1) with transmittance of ∼77% over the fabricated area, 18 × 15 cm2. By joule heating using few volts, uniform temperatures up to 170 °C were achieved on the electrode area and a high thermal resistance of 255.2 °C cm2 W−1 was obtained. The electrode was tested for defrosting application by exposing it to liquid nitrogen (LN2) vapors at ∼−60 °C while applying 8.5 V for 2 min, when the frost disappeared making the display board below, visible. The transparent heater could successfully withstand an ultrasonication test, as well as many defrosting cycles.

66 citations


Cited by
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Journal ArticleDOI
TL;DR: A variety of strategies such as structural tuning, composition control, doping, hybrid structures, heterostructures, defect control, temperature effects and porosity effects on metal sulfide nanocrystals are discussed and how they are exploited to enhance performance and develop future energy materials.
Abstract: In recent years, nanocrystals of metal sulfide materials have attracted scientific research interest for renewable energy applications due to the abundant choice of materials with easily tunable electronic, optical, physical and chemical properties. Metal sulfides are semiconducting compounds where sulfur is an anion associated with a metal cation; and the metal ions may be in mono-, bi- or multi-form. The diverse range of available metal sulfide materials offers a unique platform to construct a large number of potential materials that demonstrate exotic chemical, physical and electronic phenomena and novel functional properties and applications. To fully exploit the potential of these fascinating materials, scalable methods for the preparation of low-cost metal sulfides, heterostructures, and hybrids of high quality must be developed. This comprehensive review indicates approaches for the controlled fabrication of metal sulfides and subsequently delivers an overview of recent progress in tuning the chemical, physical, optical and nano- and micro-structural properties of metal sulfide nanocrystals using a range of material fabrication methods. For hydrogen energy production, three major approaches are discussed in detail: electrocatalytic hydrogen generation, powder photocatalytic hydrogen generation and photoelectrochemical water splitting. A variety of strategies such as structural tuning, composition control, doping, hybrid structures, heterostructures, defect control, temperature effects and porosity effects on metal sulfide nanocrystals are discussed and how they are exploited to enhance performance and develop future energy materials. From this literature survey, energy conversion currently relies on a limited range of metal sulfides and their composites, and several metal sulfides are immature in terms of their dissolution, photocorrosion and long-term durability in electrolytes during water splitting. Future research directions for innovative metal sulfides should be closely allied to energy and environmental issues, along with their advanced characterization, and developing new classes of metal sulfide materials with well-defined fabrication methods.

685 citations

Journal ArticleDOI
01 Nov 2016-Small
TL;DR: Recent progress on the main applications reported for MNW networks of any sort (silver, copper, gold, core-shell nanowires) are investigated and some of the most impressive outcomes are pointed out.
Abstract: Transparent electrodes attract intense attention in many technological fields, including optoelectronic devices, transparent film heaters and electromagnetic applications. New generation transparent electrodes are expected to have three main physical properties: high electrical conductivity, high transparency and mechanical flexibility. The most efficient and widely used transparent conducting material is currently indium tin oxide (ITO). However the scarcity of indium associated with ITO's lack of flexibility and the relatively high manufacturing costs have a prompted search into alternative materials. With their outstanding physical properties, metallic nanowire (MNW)-based percolating networks appear to be one of the most promising alternatives to ITO. They also have several other advantages, such as solution-based processing, and are compatible with large area deposition techniques. Estimations of cost of the technology are lower, in particular thanks to the small quantities of nanomaterials needed to reach industrial performance criteria. The present review investigates recent progress on the main applications reported for MNW networks of any sort (silver, copper, gold, core-shell nanowires) and points out some of the most impressive outcomes. Insights into processing MNW into high-performance transparent conducting thin films are also discussed according to each specific application. Finally, strategies for improving both their stability and integration into real devices are presented.

445 citations

Journal ArticleDOI
TL;DR: In this article, a review of recent progress in smart windows of each category is overviewed with particular focus on functional materials, device design, and performance enhancement, followed by a discussion of emerging technologies such as dual stimuli triggered smart window and integrated devices toward multifunctionality.
Abstract: Smart window refers to the on-demand window that can dynamically modulate light transmittance. It is recognized as a promising technology to economize building energy A smart window that dynamically modulates light transmittance is crucial for building energy efficiently, and promising for on-demand optical devices. The rapid development of technology brings out different categories that have fundamentally different transmittance modulation mechanisms, including the electro-, thermo-, mechano-, and photochromic smart windows. In this review, recent progress in smart windows of each category is overviewed. The strategies for each smart window are outlined with particular focus on functional materials, device design, and performance enhancement. The advantages and disadvantages of each category are summarized, followed by a discussion of emerging technologies such as dual stimuli triggered smart window and integrated devices toward multifunctionality. These multifunctional devices combine smart window technology with, for example, solar cells, triboelectric nanogenerators, actuators, energy storage devices, and electrothermal devices. Lastly, a perspective is provided on the future development of smart windows. Smart Windows

375 citations

Journal Article
TL;DR: Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells.
Abstract: Solar-energy conversion usually takes one of two forms: the 'quantum' approach, which uses the large per-photon energy of solar radiation to excite electrons, as in photovoltaic cells, or the 'thermal' approach, which uses concentrated sunlight as a thermal-energy source to indirectly produce electricity using a heat engine. Here we present a new concept for solar electricity generation, photon-enhanced thermionic emission, which combines quantum and thermal mechanisms into a single physical process. The device is based on thermionic emission of photoexcited electrons from a semiconductor cathode at high temperature. Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells. The proposed solar converter would operate at temperatures exceeding 200 degrees C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50%.

319 citations

Journal ArticleDOI
TL;DR: In this article, a review of printable inks based on conductive nanomaterials is presented, which summarizes basic principles and recent development of common printing technologies, formulations of printed inks, deposition of conductive inks via different printing techniques, and performance enhancement by using various sintering methods.
Abstract: DOI: 10.1002/admt.201800546 manufacturing processes and relatively high production cost.[12,13] PE has been explored for the manufacturing of flexible and stretchable electronic devices by printing functional inks containing soluble or dispersed materials,[14–16] which has enabled a wide variety of applications, such as transparent conductive films (TCFs), flexible energy harvesting and storage, thin film transistors (TFTs), electroluminescent devices, and wearable sensors.[17–24] The global PE market should reach $26.6 billion by 2022 from $14.0 billion in 2017 at a compound annual growth rate of 13.6%.[25] PE devices are manufactured by a variety of printing technologies. Typical printing technologies can be divided into two broad categories: noncontact patterning (or nozzle-based patterning) and contact-based patterning. The noncontact techniques include inkjet printing, electrohydrodynamic (EHD) printing, aerosol jet printing, and slot die coating, while screen printing, gravure printing, and flexographic printing are examples of the contact techniques. Each of these techniques has its own advantages and disadvantages, but they all rely on the principle of transferring inks to a substrate. Understanding the characteristics and recent advances of each printing technique is important to further the progress in PE. Moreover, to promote the lab-scale printing technologies to large-scale production process, roll-toroll (R2R) printing, which is one of the manufacturing methods to obtain large-area films with low cost and excellent durability, has drawn much attention from both industry and the research community. Nearly all of devices based on PE require conductive structures, interconnects, and contacts; therefore, highly conductive patterns, usually with high transparency and/or high resolution, fabricated by means of printing conductive materials are one of the most critical components in PE devices. Various printable conductive nanomaterials, such as metal nanomaterials (e.g., metal nanoparticles and metal nanowires) and carbon nanomaterials (e.g., graphene and carbon nanotubes (CNTs)), have been explored and used as major materials for PE. Applying printing technology to deposition of the conductive nanomaterials requires formulation of suitable inks. After depositing inks on different substrates, post-printing treatment, Printed electronics is attracting a great deal of attention in both research and commercialization as it enables fabrication of large-scale, low-cost electronic devices on a variety of substrates. Printed electronics plays a critical role in facilitating widespread flexible electronics and more recently stretchable electronics. Conductive nanomaterials, such as metal nanoparticles and nanowires, carbon nanotubes, and graphene, are promising building blocks for printed electronics. Nanomaterial-based printing technologies, formulation of printable inks, post-printing treatment, and integration of functional devices have progressed substantially in the recent years. This review summarizes basic principles and recent development of common printing technologies, formulations of printable inks based on conductive nanomaterials, deposition of conductive inks via different printing techniques, and performance enhancement by using various sintering methods. While this review places emphasis on conductive nanomaterials, the printing techniques and ink formulations can be applied to other materials such as semiconducting and insulating nanomaterials. Moreover, some applications of printed flexible and stretchable electronic devices are reviewed to illustrate their potential. Finally, the future challenges and prospects for printing conductive nanomaterials are discussed.

310 citations