Nanostructured solar cells

Conversion into electrical power of even a small fraction of the solar radiation
incident on the Earth’s surface has the potential to satisfy the world’s energy demands without generating CO2 emissions. Current photovoltaic technology is
not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be
underestimated, a major bottleneck lies in the photovoltaic devices themselves.
Improving efficiency is part of the solution, but diminishing returns in that area
mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes.

Solution-processible materials, e.g. organic molecules, conjugated polymers
and semiconductor nanoparticles, offer new routes to the low-cost production of
solar cells. The challenge here is that absorbing light in an organic material
produces a coulombically bound exciton that requires dissociation at a
donor–acceptor heterojunction. A thickness of at least 100 nm is required to
absorb the incident light, but excitons only diffuse a few nanometres before
decaying. The problem is therefore intrinsically at the nano-scale: we need
composite devices with a large area of internal donor–acceptor interface, but
where each carrier has a pathway to the respective electrode. Dye-sensitized and
bulk heterojunction cells have nanostructures which approach this challenge in
different ways, and leading research in this area is described in many of the
articles in this special issue.

This issue is not restricted to organic or dye-sensitized photovoltaics, since
nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at surfaces and interfaces, which are often the limiting factor in device performance.

This issue provides concrete examples of how the techniques of nanoscience and nanotechnology can be used to understand, control and optimize the performance of novel photovoltaic devices.

Nanostructure Fabrication Processes

Progress in understanding and optimizing materials processing in wet chemical environments requires the use of in situ measurements of the structure and dynamics of the metal-electrolyte interface under realistic conditions. These measurements can provide insight into the mechanisms of relevant atomic, molecular, and mesoscale film growth and dissolution processes.

This project has several thrust areas ranging from measurements and modeling of surfactant mediated growth to the investigation of both surface and thin film growth stress. Particular attention has been given to the role of electrolyte additives in the formation and performance of advanced nanoscale and mesoscale interconnects as used in state of the art microelectronic devices. Measurements are also underway that detail the use of underpotential deposition (upd) reactions to precisely control the composition and structure of 2-D and 3-D alloys. This is complemented by measurements of stress changes that accompany alloy formation as well as the inverse dealloying process. An integral part of the program is the development of mechanistic linkage between atomic and molecular phenomena and rational design of the desired nanostructures.

Additional Technical Details:
This year we demonstrated the first example of void-free trench filling with ferromagnetic materials. Feature filling involves a new mechanism of superconformal growth that uses a single inhibitor whose consumption during deposition gives rise to positive feedback. Coupling of the non-linear dynamics with the non-planar substrate geometry gives rise to void-free nickel deposition in the recessed surface features as shown in the cross section TEM images given below. Two types of molecules have been shown to yield this effect; cationic Nbearing polymers and more recently certain benzimidazole derivatives. The latter provide feature filling dynamics that offer seamless integration with conventional Damascene processing and thereby the prospect of introducing ferromagnetic materials into 3-D metallization for ULSICMOS and MEMS applications.

Measurements developed for upd processes of alloy deposition have received significant attention in the past year. Practical interest in the production of Pt-transition metal alloys for use as either hard magnetic materials for memory applications and /or as potential fuel cell electrocatalyst has motivated much of this work. The Pt-Cu system has been examined as a model upd-codeposition system due to the absence of parasitic reactions. As shown below, co-deposition of Cu with Pt occurs at potentials well positive of that required to deposit pure Cu. The figure also demonstrates the use of in situ quartz crystal gravimetry for the determination of alloy composition along with a direct comparison to post deposition ex-situ methods.

The upd process has also been applied to Pt-Ni and Pt-Co alloys and preliminary studies indicate that these alloy films are more catalytic than pure Pt for the oxygen reduction reaction; the latter being a central impediment to improved fuel cell performance.

In order to gain a deeper insight into upd and molecular adsorption processes relevant to a wide range of electrochemical processing issues, a variety of in situ scanning tunneling microscope (STM), atomic force microscope (AFM), stress and gravimetric measurements are underway.

MSEL has recently constructed an optical bench for in situ measurement of surface stress during electrochemical processing using the wafer curvature method. Forces on the order of 0.008 N/m (23 km radius of curvature) can be resolved, sufficient to study the adsorption of upd and molecular monolayers. This powerful method is capable of monitoring the surface stress associated with reversible upd reactions such as Pb onto the (111)-textured Au surface as shown below.

The stress transient shows four regimes of behavior from ClO4- desorption, Pb-Au bond formation, stress relaxation due to hcp-Pb island coalescence, and electrocompression of the monolayer at potentials just positive of bulk Pb deposition. Interestingly, these measurements show that the complete Pb monolayer behaves as a free-standing elastic film where the stress - strain proportionality has a value equal to the biaxial modulus for Pb (111) in the bulk. Similar work has examined the upd of Bi on Au. Further work is underway exploring these timely and exciting issues.

Nanostructure

A nanostructure is an object of intermediate size between molecular and microscopic (micrometer-sized) structures.

In describing nanostructures it is necessary to differentiate between the number of dimensions on the nanoscale. Nanotextured surfaces have one dimension on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length could be much greater. Finally, spherical nanoparticles have three dimensions on the nanoscale, i.e., the particle is between 0.1 and 100 nm in each spatial dimension. The terms nanoparticles and ultrafine particles (UFP) often are used synonymously although UFP can reach into the micrometre range. The term 'nanostructure' is often used when referring to magnetic technology.

List of nanostructures

• Nanocages
• Nanocomposite
• Nanofabrics
• Nanofiber
• Nanoflake
• Nanoflower
• Nanofoam
• Nanomesh
• Nanoparticle
• Nanopillar
• Nanopin film
• Nanoring
• Nanorod
• Nanoshell
• Quantum dot
• Quantum heterostructure
• Sculptured thin film

Nanotechnology and its Future Applications

Nanotechnology

Nanotechnology, the term coined by Eric Drexler in the1980s, refers to the engineering of tiny devices and machines. This is a technology involving the potential ability to fabricate structures and devices with atomic precision by controlling the size of the matter at the scale of 1-10nm. It will provide the solution to a large number of problems faced by mankind today. A nanometer is one billionth of a meter (10-9), roughly the width of three or four atoms.

The Potential of Nanotechnology

The potential of nanotechnology is huge and can lead to tremendous miniaturization in wider areas like space systems, medial diagnostic equipments and drug delivery systems. It will enable us to fabricate very sensitive devices and machines, leading to the enhancement of human capabilities to work efficiently, at lowers cost, with more precision and in environmentally friendly ways. Nanotechnology will make it feasible for us to create such sophisticated devices and structures with more flexibility at nanoscale.

Areas in which nanotechnology has future applications and discoveries, which can lead to enormous economical and industrial development, is as follows:

• Macromolecular design and folding
• Self-assembly methods
• Catalysis (inorganic, enzyme and other)
• Dendrimers, fullerenes and other novel chemical structures
• Bioenergetics, nanobatteries and ultrasound-driven chemistry
• Semiconductor-organic/biological interfaces
• Miniaturization and massive parallelism of SFM
• Molecular modeling tool

Applications:

• Energy Storage, Production and Conversion:
  a) Novel hydrogen storage systems based on carbon nanotubes and other
  lightweight nanomaterials
  b) Photovoltaic cells and organic light-emitting devices based on quantum dots
  c) Carbon nanotubes in composite 0.lm coatings for solar cells
  d) Nanocatalysts for hydrogen generation
  e) Hybrid protein-polymer biomimetic membranes
• Agricultural Productivity Enrichment:
  a) Nanoporous zeolites for slow release and efficient dosage of water and
  fertilizers for plants and of nutrients and drugs for livestock
  b) Nanocapsules for herbicide delivery
  c) Nanosensors for soil quality and for plant health monitoring
  d) Nanomagnets for removal of soil contaminants
• Water Treatment and Remediation:
  a) Nanomembranes for water purification, desalination and detoxification
  b) Nanosensors for the detection of contaminants and pathogens
  c) Nanoporous zeolites, nanoporous polymers and attapulgite clays for water purification
  d) Magnetic nanoparticles for water treatment and remediation
  e) TiO 2 nanoparticles for the catalytic degradation of water pollutants
• Disease Diagnosis and Screening:
  a) Nanoliter systems (Lab-on-a-chip)
  b) Nanosensor arrays based on carbon nanotubes
  c) Quantum dots for disease diagnosis
  d) Magnetic nanoparticles as nanosensors
  e) Antibody-dendrimer conjugates for diagnosis of HIV-1 and cancer
  f) Nanowire and nanobelt nanosensors for disease diagnosis
  g) Nanoparticles as medical image enhancers
• Drug Delivery Systems:
  a)Nanocapsules, liposomes, dendrimers, buckyballs, nanobiomagnets
  and attapulgite clays for slow and sustained drug release systems
• Food Processing and Storage:
  a) Nanocomposites for plastic .lm coatings used in food packaging
  b) Antimicrobial nanoemulsions for applications used in decontamination of food equipment or packaging
  c) Nanotechnology-based antigen detecting biosensors for identification of pathogen contamination
• Air Pollution and Remediation:
  a) TiO 2 nanoparticle-based photocatalytic degradation of air pollutants in
  self-cleaning systems
  b) Nanocatalysts for more efficient, cheaper and better-controlled
  catalytic converters
  c) Nanosensors for detection of toxic materials and leaks
  d) Gas separation nanodevices
• Construction - nanomolecular structures to make asphalt and concrete more robust to counter water seepage:
  a) Heat-resistant nanomaterials to block ultraviolet and infrared radiation
  b) Nanomaterials for cheaper and durable housing, surfaces, coatings, glues, concrete and heat and light exclusion
  c) Self-cleaning surfaces (e.g. windows, mirrors, toilets) with bioactive coatings
• Health monitoring Nanotubes and nanoparticles for glucose, CO(2), and cholesterol sensors and for in-site monitoring of homeostasis:
• Vector and pest detection and control:
  a) Nanosensors for pest detection.
  b) Nanoparticles for new pesticides, insecticides and insect repellents

Nanotechnology and Cancer

Majority of animal cells are approximately 10,000 to 20,000 nanometers in width. Consequently, it would be simpler for nano tools to go into and intermingle with the cell's proteins and DNA.

Nanotechnology can be utilized to combat cancer in 2 manners. Firstly, it will be utilized in spotting the existence of cancer much sooner and with superior accuracy as compared to the regular diagnostic techniques, like X-RAYS, MRIs, and biopsies. Secondly, it will be utilized in the obliteration of the cancer, with bigger exactitude and diligence, once it is diagnosed.

Nanotechnology Cancer Treatment

Nanotechnology's supreme guarantee in medical history is its probability to obliterate cancers that up till now have been defiant to conservative cures.

Contemporary radiation and chemotherapy can be best defined as 'carpet bombing' cancer. That implies that fit cells are assaulted together with the cancer cells. The consequence is that the cancer patient undergoes severe spin-offs, together with sickness, hair fall, anemia, and the dilapidation of his/her immunology. The deficiency of accuracy inbuilt in contemporary cancer combating methods at times, implies that not the entire of a cancer is eliminated, leading to a revival of the cancer.

Nanotechnology cancer therapy on the other hand, gives the probability of a cancer combating smart method. Nano tools can be developed that can accurately transport medicines to only the cancer cells, leaving fit cells undamaged. These tools would go into the formerly distinguished cancerous cells and carry the drug or amalgamation of drugs, annihilating the cancer from its roots.

One more prospective system blends nanotechnology with an innovative type of radiation therapy. Carbon nano tubes are set up into cancerous cells. After that an infrared laser is emphasized on the impacted region. The laser warms the nano tubes, leading to the damage of the cancerous cells, leaving fit cells unharmed.

An additional method anticipated for curing cancer would entail nano computers factually redrafting the DNA of cancerous cells to transform them back into standard cells. The concept would be that these tools would inspect the DNA of cancerous cells on the minuscule level, contrasting them to what the DNA of usual cells for the cancer patient ought to be, and then calling in nano fixing devices to repair the DNA.

Summary

This implies that within the life span of majority people, cancer- the big slayer of our time, may no more be laden with the terror we see it with now. The next generation might well see cancer as we see few epidemics from history, such as chicken pox, which are a fraction of history and no more as an element of our daily life.

Nanotechnology and it's Benefits

Nanotechnology is a protective coating that enhances products of any sort of material. It can strengthen and improve the assets to benefit both manufacturers and end users. With the help of Nanotechnology, which is an applied science, new products are created to protect various materials.

Protective coating is a result of nanotechnology. It makes the materials weather resistant and the surface becomes easy to clean as well. Its protective coating exhibits very high resistance to corrosion attack, long term stability in aggressive conditions and an environmentally friendly, easy and economical preparation procedure.

Nanotechnology and its characteristics will be different in the case of each material surface and it is available with standard features and techniques. Nanotechnology uses more techniques and tools for its updating. Nanotechnology research has been made continuously to update technology using different techniques and tools available in the world. New technologies have been used to measure the molecular interactions that take place.

Nanotechnology has the potential to revolutionize the life of materials used in every sector be it industrial, residential, medicines, genetics, communication, textile and many more. It helps to improve products and production processes with better techniques and new functionality.

In coming years, products based on nanotechnology are expected to impact nearly all-industrial sectors and enter the consumer markets in large quantities. Considering the future prospects of nanotechnology, countries across the world are investing heavily in this sector. Diamon Fusion International is one such example that makes the optimum use of nanotechnology by providing glass protection,hydrophobic coating, protective coating to various materials depending on there characters.

Nanotechnology - Nanomedicine

Nanotechnology involves the science and technology of devices and materials, such as drug delivery systems or electronic circuits, that are created on extremely tiny scales – as small as molecules and even atoms. Nanotechnology also involves manipulation of structure matter at molecular levels, involving different fields and specialties such as chemistry, engineering, electronics, medicine and others. All of these fields of study and pursuit are concerned with bringing existing technologies down to a very tiny scale that is measured in, 'nanometers,' which is a billionth of a meter, or about the size of six carbon atoms in a row.

The processes used both today and in the past in the creation of industrial products have involved pushing piles of millions of atoms together through mixing, grinding and heating, a process that is very imprecise. Scientists are now able to pick up individual atoms and assemble them into structures, or cause particular chemical reactions. For example, propellers have been attached to molecular motors and electricity has been conducted through, 'nanowires.' 'Nanotubes,' made of carbon are being investigated for use in a variety of both research and industrial purposes. As the future approaches, the use of nanotechnology might find scientists able to harness the forces that operate at the scale of the nanometer, such as the Van Der Waals force. They may be able to harness the changes in the quantum states of particles for engineering purposes.

One of the promising aspects of nanotechnology where improvement of the quality of human life is concerned includes the potential for new treatments for disease. Tiny autonomous robots or, 'nanobots,' might one day be sent into a person's body to cure cancer or repair cells, or possibly even extend the person's life span by a number of years. At this time the simple devices that have been created by nanotechnology are not of the complexity envisioned with nanomachines and nanobots.

Nanotechnology Background

Nanotechnology has emerged from the chemical, physical, biological and engineering sciences. Novel techniques are being developed by scientists in these fields to both probe and manipulate individual atoms and molecules. The tools these scientists have developed have enabled a variety of new discoveries regarding the ways in which properties of matter are governed by the atomic and molecular arrangements at nanometer dimensions. The discoveries that have been made have had an impact on the processing of a wide-range of devices and materials. The results have been substantial improvements in existing technologies, as well as entirely new ones. Control of the design properties, materials, as well as devices at the nanoscale is possible through exploitation of strategies which are often complemented by top-down engineering approaches.

Nanotechnology-based approaches are poised to revolutionize research biology and medicine. In another example, with the significant progress in understanding the genetic basis of biochemical pathways that are involved in both injury and disease processes, there is a great need for highly-sensitive, real-time monitoring and detection technologies. Nanotechnology may be used to design diagnostic systems that are multi-functional and multi-analytic; ones that not only define early stage changes or progression of disease states, but also identify unique biological molecules, structures and chemicals. There are nanotechnologies related to imaging for metastasis, inflammation, and angiogenesis that are emerging. Nanotechnology and nanoscience are presenting new opportunities for the treatment and management of traumatic injuries and diseases. Multifunctional materials on nanoscales that capitalize on progress in proteomics and genomics are allowing targeted delivery of molecular therapies with enhanced efficacy.

Studies that use nanotechnology concepts and techniques and focus on biological processes have the potential to provide new insight into the physical relationships between cellular components and functional irregularities that trigger pathological abnormalities. Nanoscience and the technologies emerging from it offer a means of controlling the design and assembly of biomolecular processes that are very relevant to health and disease. In another example, while the processes involved in energy conversion offer a means of constructing a biomolecular machine through enzymology and structural biology have been studied for a number of years, nanotechnology and nanoscience present a means of creating a biomolecular machine that uses biological energy sources in new ways.

NanoTechnology, Nanomedicine, and the Future

Nanotechnologies, applied to the medical field, could allow doctors to search out and destroy the very first cancer cells that would otherwise have caused a tumor to develop. Nanotechnologies could remove a broken portion of a cell and replace it with a miniature biological machine, or deliver medicines exactly where and when they are needed. Nanomedicine is an offshoot of nanotechnology, and refers to highly-specific medical intervention at the molecular scale for curing diseases or repairing damaged tissues. The pursuit of nanomedicine on the part of researchers at the National Institute of Health (NIH) began several years ago, with results expected within ten years of their launch date in 2005.

Research into nanotechnology started with discoveries of unique chemical and physical properties of various carbon-based or metallic materials which only appear for structures at nanometer-sized dimensions. The ability to understand the scale of these properties allows engineers to build new structures and use the materials in new ways. The same thing is true for biological structures inside living cells within the human body. Researchers have been able to develop powerful tools to categorize the parts of cells in great detail; they are aware of a great amount of detail concerning how intracellular structures operate.

Still, scientists have not been able to answer certain questions. The questions that remain involve things such as, 'How many, ' 'how big,' and, 'how fast?' They must find the answers to these kinds of questions in order to fully understand cellular structures and gain the ability to repair them, or build new nanotechnology structures that can safely operate inside the human body. Once scientists have achieved this, they will be able to work with others to build better diagnostic tools and engineer nanoscale structures for specific treatments of diseases or tissues that have been damaged.

The NIH established a national network of eight Nanomedicine Development Centers to serve as the intellectual and technological centerpiece of the NIH Nanomedicine Roadmap Initiative. The centers are staffed by research teams that include physicians, biologists, engineers, mathematicians, and computer scientists. The initial phase of the program found the centers pursuing research aimed at gathering extensive information about the chemical and physical properties of nanoscale biological structures. Because of the catalogue the NIH has been able to create, they are gaining a greater understanding of nature's rules of biological design that will enable their researchers to correct defects in unhealthy cells. The research requires the development of new devices for a broad range of biomedical applications, such as detecting infectious agents or metabolic imbalances, with new and tiny sensors, replacing items inside of cells with new nanoscale structures, or generating miniature devices that have the capability to search for and destroy infectious agents.

The NIH is approaching phase two of the program, which has been approved. During phase two of the Nanomedicine initiative, the fundamental knowledge and developed tools they have acquired will be applied to both understanding and treatment of disease. The centers will continue their pursuit of knowledge, expanding it in regards to the science of nanostructures in living cells. They will gain the capability to engineer biological nanostructures, apply their knowledge, tools, and devices – and focus on targeting specific diseases.