S. Ravi P. Silva
University of Surrey, Advanced Technology Institute, Faculty Member
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... of Electronics, Massachusetts Institute of Technology, Building 36-876, 77 Massachusetts Avenue,Cambridge, Massachusetts 02139 AADT Adikaari, V. Stolojan, and SRP Silva Nanoelectronic Centre Advanced Technology Institute, University... more
... of Electronics, Massachusetts Institute of Technology, Building 36-876, 77 Massachusetts Avenue,Cambridge, Massachusetts 02139 AADT Adikaari, V. Stolojan, and SRP Silva Nanoelectronic Centre Advanced Technology Institute, University of Surrey, Guildford, Surrey GU2 ...
Research Interests: Materials Engineering, Aerospace Engineering, Materials Science, Laser, Transmission Electron Microscopy, and 13 moreHigh Energy Density Physics, Atomic Force Microscopy, Field emission, Atmospheric sciences, Field Electron Emission, Nanocomposite, Vacuum, Nanoclusters, Structural Properties, Ion Beam, Excimer Laser, Vacuum Science and Technology, and energy density
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Halide perovskite materials have been extensively explored for their unique electrical, optical, magnetic, and catalytic properties. Most notably, solar cells based on perovskite thin films have improved their power conversion efficiency... more
Halide perovskite materials have been extensively explored for their unique electrical, optical, magnetic, and catalytic properties. Most notably, solar cells based on perovskite thin films have improved their power conversion efficiency from 3.8% to over 25% during the last 12 years. However, it is still a challenge to develop a perovskite-based ink, suitable for upscaling the fabrication process of high-quality perovskite films with extreme purity, good crystallinity, and complete coverage over the deposition area. This is particularly important if the perovskite films are to be used for the scaled production of optoelectronic devices. Therefore, to make halide perovskites commercially available for various applications, it is vital to develop a reliable and highly robust deposition method, which can then be transferred to industry. Herein, the development of perovskite precursor inks suitable for use at low-temperature and vacuum-free solution-based deposition processes is report...
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PDMS is used as matrix to produce a flexible supercapacitor based on aligned carbon nanotubes and polyaniline, which presents outstanding energy-to-power density ratio and remarkable cycling stability even at different bending angles.
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For system-on-panel (SoP) integration, due to the substrate of poor thermal conductivity, the generated heat in the device channel can not be dissipated efficiently, thus causing serious self-heating effects. In this letter, such... more
For system-on-panel (SoP) integration, due to the substrate of poor thermal conductivity, the generated heat in the device channel can not be dissipated efficiently, thus causing serious self-heating effects. In this letter, such electro-thermal effects in analog thin-film transistors (TFTs) in SoP integration are investigated and compared with that in SOI technologies by numerical device simulation. The analysis highlights much more significant self-heating effects in SoP integration. A possible way to improve the thermal analog performance of the TFT is also discussed.
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ABSTRACT Rapid prototyping of photovoltaic (PV) cells requires a method for the simultaneous simulation of the optical and electrical characteristics of the device. The development of nanomaterial-enabled PV cells only increases the... more
ABSTRACT Rapid prototyping of photovoltaic (PV) cells requires a method for the simultaneous simulation of the optical and electrical characteristics of the device. The development of nanomaterial-enabled PV cells only increases the complexity of such simulations. Here, we use a commercial technology computer aided design (TCAD) software, Silvaco Atlas, to design and model plasmonic gold nanoparticles integrated in optoelectronic device models of thin-film amorphous silicon (a-Si:H) PV cells. Upon illumination with incident light, we simulate the optical and electrical properties of the cell simultaneously and use the simulation to produce current–voltage (J − V) and external quantum efficiency plots. Light trapping due to light scattering and localized surface plasmon resonance interactions by the nanoparticles has resulted in the enhancement of both the optical and electrical properties due to the reduction in the recombination rates in the photoactive layer. We show that the device performance of the modeled plasmonic a-Si:H PV cells depends significantly on the position and size of the gold nanoparticles, which leads to improvements either in optical properties only, or in both optical and electrical properties. The model provides a route to optimize the device architecture by simultaneously optimizing the optical and electrical characteristics, which leads to a detailed understanding of plasmonic PV cells from a design perspective and offers an advanced tool for rapid device prototyping.
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The electronic conduction mechanism occuring in amorphous thin films is quite complicated. In amorphous carbon films it is further exacerbated by the rich diversity of its microstructure as well as the large number of gap states present... more
The electronic conduction mechanism occuring in amorphous thin films is quite complicated. In amorphous carbon films it is further exacerbated by the rich diversity of its microstructure as well as the large number of gap states present in the films. One of the main reasons for the tunability of the optical band gaps of these films not being exploited in active devices, has been the inability firstly to reduce the gap states to an acceptable level, and secondly finding suitable dopants that are electrically active at room temperature. The large number of gap states in the films further exacerbates its problems by not allowing suitable barriers (eg. Schottky) to be formed on to the amorphous carbon films. In this paper we hope to first divide the amorphous carbon thin films into two main categories. Namely, diamond-like carbon films which have a high precentage of C-C sp 3 bonding, and polymer-like carbon films that also have a high percentage of sp 3 bonding which is a mixture of C-C and C-H bonds, and have a high percentage of hydrogen as well as large optical band gaps. Recent results based on ion implantation using ions such as N, B, C will be contrasted to in-situ dopant incorporation via a gaseous source., and is shown to be a very powerful technique of modifying the conduction properties. It will be shown that in the diamond-like films the conduction properties are usually controlled via Poole-Frenkel type defect conduction, while for the polymer-like films it is more a space charge based bulk and possibly, barrier controlled process. But, due to the large band gaps of these films it is difficult to distinguish between the bulk effects and the barrier effects.
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ABSTRACT Indium Tin Oxide (ITO) coated glass is currently the preferred transparent conducting electrode (TCE) for organic light emitting diodes (OLEDs). However, ITO has its drawbacks, not least the scarcity of Indium, high processing... more
ABSTRACT Indium Tin Oxide (ITO) coated glass is currently the preferred transparent conducting electrode (TCE) for organic light emitting diodes (OLEDs). However, ITO has its drawbacks, not least the scarcity of Indium, high processing temperatures, and inflexibility. A number of technologies have been put forward as replacements for ITO. In this paper, an OLED based on a gold grid TCE is demonstrated, the light emission through the grid is examined, and luminance and current measurements are reported. The gold grid has a sheet resistance of 15 Ω□-1 and a light transmission of 63 % at 550 nm, comparable to ITO, but with advantages in terms of processing conditions and cost. The gold grid OLED has a lower turn-on voltage (7.7 V versus 9.8 V) and achieves a luminance of 100 cdm-2 at a lower voltage (10.9 V versus 12.4 V) than the reference ITO OLED. We discuss the lower turn-on voltage and the uniformity of the light output through the gold grid TCE and examine the conduction mechanisms in the ITO and gold grid TCE OLEDs.
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We demonstrate a rare combination of polymer wrapped single walled carbon nanotubes with liquid crystals to produce switchable optoelectronic devices.
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Organ injury not only occurs during periods of ischaemia, but paradoxically also during reperfusion. 1 This damage is collectively known as ischaemia-reperfusion (I/R) injury. Neutrophils and the immune response are central to I/R injury,... more
Organ injury not only occurs during periods of ischaemia, but paradoxically also during reperfusion. 1 This damage is collectively known as ischaemia-reperfusion (I/R) injury. Neutrophils and the immune response are central to I/R injury, 2, 3 as are cell adhesion ...
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The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information on “Adaptive, Active and Multifunctional Smart Materials Systems”. The papers are conveniently arranged into: Chapter 1: Smart Inorganic... more
The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information on “Adaptive, Active and Multifunctional Smart Materials Systems”. The papers are conveniently arranged into: Chapter 1: Smart Inorganic Materials Systems, Chapter 2: Stimuli Responsive Polymers and Gels, Chapter 3: Luminescent and Chromogenic Materials Systems, Chapter 4: Multifunctional Composites and Porous Materials Systems, Chapter 5: Non-Volatile Memory Devices, Chapter 6: Multiferroics, Chapter 7: Metamaterials, Chapter 8: Graphene, Chapter 9: Multifunctional Materials for Energy Harvesting, Chapter 10: Actively Moving Polymers
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... 10:36 AM10:48 AM. Preview Abstract. Authors: David Carey Richard Smith Ravi Silva (University of Surrey). The high aspect ratio and current carrying ability of carbon nanotubes (CNTs) make them an attractive material for electron... more
... 10:36 AM10:48 AM. Preview Abstract. Authors: David Carey Richard Smith Ravi Silva (University of Surrey). The high aspect ratio and current carrying ability of carbon nanotubes (CNTs) make them an attractive material for electron sources. ...
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Steam treatment has been applied to our prefabricated highly aligned areas of electrospun carbon nanotube composite nano-fibres, leading to controlled and targeted removal of polymeric and amorphous carbon materials, resulting in areas of... more
Steam treatment has been applied to our prefabricated highly aligned areas of electrospun carbon nanotube composite nano-fibres, leading to controlled and targeted removal of polymeric and amorphous carbon materials, resulting in areas of highly aligned, highly crystalline, pure nanotubes. Raman analysis shows how the ID to IG intensity ratio was reduced to 0.03, and the radial breathing mode peak intensity, used for nanotube diameter calculation, changes. Therefore, suggesting that some carbon nanotubes are more resistant to steam assisted oxidation, meaning that specific carbon nanotube diameters are preferentially oxidised. The remaining carbon nanotubes have displayed a significant improvement in both quality, with respect to defect density, and in crystallinity, resulting in an increased resistance to oxidation. These steam treated super resilient carbon nanotubes are shown to withstand temperatures of above 900 °C under ambient conditions. Applying this purification method to electrospun nano-fibres leads the way for the next generation of composite materials which can be used in high temperature extreme environments.
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The photoluminescence spectra of a series of 5-substituted pyridyl-1,2,3-triazolato Pt(II) homoleptic complexes show weak emission tunability (ranging from λ=397-408 nm) in dilute (10(-6) M) ethanolic solutions at the monomer level and... more
The photoluminescence spectra of a series of 5-substituted pyridyl-1,2,3-triazolato Pt(II) homoleptic complexes show weak emission tunability (ranging from λ=397-408 nm) in dilute (10(-6) M) ethanolic solutions at the monomer level and strong tunability in concentrated solutions (10(-4) M) and thin films (ranging from λ=487-625 nm) from dimeric excited states (excimers). The results of density functional calculations (PBE0) attribute this "turn-on" sensitivity and intensity in the excimer to strong Pt-Pt metallophilic interactions and a change in the excited-state character from singlet metal-to-ligand charge transfer ((1) MLCT) to singlet metal-metal-to-ligand charge transfer ((1) MMLCT) emissions in agreement with lifetime measurements.
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A method for preparing hybrid carbon nanotube/polymer material is disclosed, the method comprising the steps of applying an ultrasonic process to a solution comprising carbon nanotubes (12) and a conjugated polymer (14) to substantially... more
A method for preparing hybrid carbon nanotube/polymer material is disclosed, the method comprising the steps of applying an ultrasonic process to a solution comprising carbon nanotubes (12) and a conjugated polymer (14) to substantially wrap or coat the carbon nanotubes with the polymer, and removing the excess polymer from the solution. Transistor devices incorporating the material exhibit narrow band gap, high mobility and p-type properties. Photovoltaic device results showing 30-40% improvement in efficiency over similar devices indicates the superior hole transport properties of the material.
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ABSTRACT The performance of nanostructured devices depend significantly on the morphology and structure of the used nanostructures. We report the hydrothermal synthesis of high quality 2D ZnO nanostructures and the fabrication of... more
ABSTRACT The performance of nanostructured devices depend significantly on the morphology and structure of the used nanostructures. We report the hydrothermal synthesis of high quality 2D ZnO nanostructures and the fabrication of ultraviolet (UV) sensors based on single 2D ZnO nanostructures. The grown nanostructures are characterized using SEM, STEM, SAED, and XRD. The single 2D ZnO nanostructure UV sensor demonstrates high photosensitivity of 980 and speed of response and recovery of 19 and 25 s, respectively. The high performance is attributed to the high quality of the ZnO 2D crystals and its high surface to volume ratio.
Graphene oxide (GO) is becoming increasingly popular for organic electronic applications. We present large active area (0.64 cm^2), solution processable,... more
Graphene oxide (GO) is becoming increasingly popular for organic electronic applications. We present large active area (0.64 cm^2), solution processable, poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:[6,6]-Phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) organic photovoltaic (OPV) solar cells, incorporating GO hole transport layers (HTL). The power conversion efficiency (PCE) of ~5% is the highest reported for OPV using this architecture. A comparative study of solution-processable devices has been undertaken to benchmark GO OPV performance with poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) HTL devices, confirming the viability of GO devices, with comparable PCEs, suitable as high chemical and thermal stability replacements for PEDOT:PSS in OPV.
... 78, 2339 (2001). AP Burden, RD Forrest, and SRP Silva, Thin Solid Films 337, 257 (1999). ... 43, 145 (1998). CH Poa, RG Lacerda, V. Stolojan, DC Cox, and SRP Silva, Proceedings of the International Conference on Metallurgical Coatings... more
... 78, 2339 (2001). AP Burden, RD Forrest, and SRP Silva, Thin Solid Films 337, 257 (1999). ... 43, 145 (1998). CH Poa, RG Lacerda, V. Stolojan, DC Cox, and SRP Silva, Proceedings of the International Conference on Metallurgical Coatings and Thin Films, ICMCTF, 2002. ...
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Iron oxide particles with the diameter being 5-10 nm were attached onto the sidewalls of multi-walled carbon nanotubes (MWCNTs) by the thermal decomposition of cyclopentadieny iron (II) dicarbonyl dimmer. The red shift of G-mode from 1579... more
Iron oxide particles with the diameter being 5-10 nm were attached onto the sidewalls of multi-walled carbon nanotubes (MWCNTs) by the thermal decomposition of cyclopentadieny iron (II) dicarbonyl dimmer. The red shift of G-mode from 1579 cm(-1) to 1571 cm(-1) in the Raman profile of the decorated MWCNTs is indicative of the attachment of nanoparticles. Electron energy loss spectroscopy and X-ray photoelectron spectroscopy analyses reveals that the attached nanoparticles are composed of a maghemite phase. Transmission electron microscopy suggests the maghemite particles are covered with amorphous carbon materials and form a core-shell structure.
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ABSTRACT Conductive patterns of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) /Multi-walled car-bon nanotubes (MWCNT) composites were deposited on glass substrates using a drop on demand (DOD) ink jet printer, with... more
ABSTRACT Conductive patterns of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) /Multi-walled car-bon nanotubes (MWCNT) composites were deposited on glass substrates using a drop on demand (DOD) ink jet printer, with the concentration of CNT varied from 0.01 to 0.05 wt. %. We show that by increasing the concentration of the nanotubes in the ink, percolated networks of well distributed carbon nanotubes in the printed samples can be achieved. Moreover, the orientation of the nanotubes in the printed sample can be controlled using a novel simple approach. The impact of the nanotube alignment on the conduction properties of inkjet printed nano-hybrid materials is studied and shown in this paper. Samples with aligned nanotubes show a 53 % enhanced conductivity in comparison with the randomly oriented nanotubes. The results show that the electrical performance of the nano-composite can be improved further by controlling the dispersion and orientation of the nano-filler in the printed samples.
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High-tech value added exports through Nanotechnology By Dhaneshi YATAWARA "Through nanotechnology we want to make products manufactured under the Sri Lankan label to be high tech, high quality products." Converting exporting items... more
High-tech value added exports through Nanotechnology
By Dhaneshi YATAWARA
"Through nanotechnology we want to make products manufactured under the Sri Lankan label to be high tech, high quality products." Converting exporting items to high tech goods is how countries like Korea achieved an advancement in economy. Doubling the nation's per capita income over the next six years and achieving a GDP growth of much greater than 8% will only be possible if sufficient investments (Public and Private) are made in research and technology. In addition, investing in Nanotechnology would help achieve the target of increasing high-tech value added exports from 1.5% to 10% by 2015, said Prof. Ravi Silva, Director of the Advance Technology Institute of the University of Surrey, UK.
By Dhaneshi YATAWARA
"Through nanotechnology we want to make products manufactured under the Sri Lankan label to be high tech, high quality products." Converting exporting items to high tech goods is how countries like Korea achieved an advancement in economy. Doubling the nation's per capita income over the next six years and achieving a GDP growth of much greater than 8% will only be possible if sufficient investments (Public and Private) are made in research and technology. In addition, investing in Nanotechnology would help achieve the target of increasing high-tech value added exports from 1.5% to 10% by 2015, said Prof. Ravi Silva, Director of the Advance Technology Institute of the University of Surrey, UK.
Uploaded by HongKongPolyU on 27 Aug 2009 In this lecture, Prof. S. Ravi P. Silva will explore the issues pertaining to the Energy Challenge posed by the human-race. How could Nanotechnology provide a glimmer of hope for... more
Uploaded by HongKongPolyU on 27 Aug 2009
In this lecture, Prof. S. Ravi P. Silva will explore the issues pertaining to the Energy Challenge posed by the human-race. How could Nanotechnology provide a glimmer of hope for revolutionising Green Energy solutions? Nanotechnology holds one of the keys to help stop the catastrophic change taking place to our global climate. The most important ingredient to make use of nanotechnologies for green energy solutions is a mind prepared to experiment and implement radical revolutionary ideas with modern know-how.
In this lecture, Prof. S. Ravi P. Silva will explore the issues pertaining to the Energy Challenge posed by the human-race. How could Nanotechnology provide a glimmer of hope for revolutionising Green Energy solutions? Nanotechnology holds one of the keys to help stop the catastrophic change taking place to our global climate. The most important ingredient to make use of nanotechnologies for green energy solutions is a mind prepared to experiment and implement radical revolutionary ideas with modern know-how.
Professor Ravi Silva, director of the Advanced Technology Institute at Surrey University, tells Alok Jha about his Clifford Patterson Lecture at the Royal Society, in which he heralds the dawn of a new carbon age – "the fifth industrial... more
Professor Ravi Silva, director of the Advanced Technology Institute at Surrey University, tells Alok Jha about his Clifford Patterson Lecture at the Royal Society, in which he heralds the dawn of a new carbon age – "the fifth industrial revolution". He believes new carbon-based materials can be created through nanotechnology that will open up new vistas in medicine and electronics.
The full lecture will shortly be made available on the Royal Society website.
The full lecture will shortly be made available on the Royal Society website.
From structure and topology, to mechanical and electronic properties, a seemingly simple change in bonding between carbon atoms can conceive a plethora of material types. With diamond and graphite known since antiquity, better... more
From structure and topology, to mechanical and electronic properties, a seemingly simple change in bonding between carbon atoms can conceive a plethora of material types. With diamond and graphite known since antiquity, better understanding of the synthesis, particularly over a large area, has enabled bottom-up design of thin films. Coupled with the discoveries of fullerenes, nanotubes and graphene, this has led to a renaissance in the study of carbon as an electronic material. With novel synthesis routes for nano-carbon production now available, the next chapter in the story of carbon is ready to be written.
S Ravi P Silva is Director of the Advanced Technology Institute and heads the Nanoelectronics Centre at the University of Surrey. In 2003 he was awarded the Albert
Einstein Silver Medal by UNESCO. He is a Fellow of the Royal Academy of Engineering, UK and a Fellow of the National Academy of Sciences, Sri Lanka. The 2011 Clifford Paterson Prize Lecture will be given by Professor S. Ravi P. Silva FREng for his outstanding contributions to basic science and engineering in the field of carbon nanoscience and nanotechnology.
S Ravi P Silva is Director of the Advanced Technology Institute and heads the Nanoelectronics Centre at the University of Surrey. In 2003 he was awarded the Albert
Einstein Silver Medal by UNESCO. He is a Fellow of the Royal Academy of Engineering, UK and a Fellow of the National Academy of Sciences, Sri Lanka. The 2011 Clifford Paterson Prize Lecture will be given by Professor S. Ravi P. Silva FREng for his outstanding contributions to basic science and engineering in the field of carbon nanoscience and nanotechnology.