Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2008
... of Electronics, Massachusetts Institute of Technology, Building 36-876, 77 Massachusetts Aven... 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 ...
Halide perovskite materials have been extensively explored for their unique electrical, optical, ... 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...
PDMS is used as matrix to produce a flexible supercapacitor based on aligned carbon nanotubes and... more 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.
For system-on-panel (SoP) integration, due to the substrate of poor thermal conductivity, the gen... 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.
ABSTRACT Rapid prototyping of photovoltaic (PV) cells requires a method for the simultaneous simu... 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.
The electronic conduction mechanism occuring in amorphous thin films is quite complicated. In amo... 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.
ABSTRACT Indium Tin Oxide (ITO) coated glass is currently the preferred transparent conducting el... 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.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2008
... of Electronics, Massachusetts Institute of Technology, Building 36-876, 77 Massachusetts Aven... 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 ...
Halide perovskite materials have been extensively explored for their unique electrical, optical, ... 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...
PDMS is used as matrix to produce a flexible supercapacitor based on aligned carbon nanotubes and... more 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.
For system-on-panel (SoP) integration, due to the substrate of poor thermal conductivity, the gen... 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.
ABSTRACT Rapid prototyping of photovoltaic (PV) cells requires a method for the simultaneous simu... 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.
The electronic conduction mechanism occuring in amorphous thin films is quite complicated. In amo... 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.
ABSTRACT Indium Tin Oxide (ITO) coated glass is currently the preferred transparent conducting el... 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.
High-tech value added exports through Nanotechnology
By Dhaneshi YATAWARA
"Through nanotech... 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.
Uploaded by HongKongPolyU on 27 Aug 2009
In this lecture, Prof. S. Ravi P. Silva will explore... 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.
Professor Ravi Silva, director of the Advanced Technology Institute at Surrey University, tells A... 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.
From structure and topology, to mechanical and electronic properties, a seemingly simple change i... 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.
Uploads
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.
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.
The full lecture will shortly be made available on the Royal Society website.
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.