<p> Given a rapidly developing world, the need exists for inexpensive renewable energy alternatives to help avoid drastic climate change. Photovoltaics have the potential to fill the energy needs of the future, but significant cost decreases are necessary for widespread adoption. Semiconductor nanocrystals, also known as quantum dots, are a nascent technology with long term potential to enable inexpensive and high efficiency photovoltaics. When deposited as a film, quantum dots form unique nanocomposites whose electronic and optical properties can be broadly tuned through manipulation of their individual constituents. </p><p> The contents of this thesis explore methods to understand and optimize the optoelectronic properties of PbSe quantum dot films for use in photovoltaic applications. Systematic optimization of photovoltaic performance is demonstrated as a function of nanocrystal size, establishing the potential for utilizing extreme quantum confinement to improve device energetics and alignment. Detailed investigations of the mechanisms of electrical transport are performed, revealing that electronic coupling in quantum dot films is significantly less than often assumed based on optical shifts. A method is proposed to employ extended regions of built-in electrical field, through controlled doping, to sidestep issues of poor transport. To this end, treatments with chemical redox agents are found to effect profound and reversible doping within nanocrystal films, sufficient to enable their use as chemical sensors, but lacking the precision required for optoelectronic applications. Finally, a novel doping method employing "redox buffers" is presented to enact precise, stable, and reversible charge-transfer doping in porous semiconductor films. An example of oxidatively doping PbSe quantum dot thin films is presented, and the future potential for redox buffers in photovoltaic applications is examined.</p>

The self–assembly of block copolymers (BCPs) into well–ordered nanoscopic arrays holds promise for new technological breakthroughs as templates and scaffolds for the fabrication of nanostructured materials. It is essential to establish convenient approaches to control the morphology of BCPs, since some applications require addressability, the BCP microdomains must be perfectly aligned and oriented. The theme of this thesis is the use of external forces, specifically thermal and solvent annealing, to guide the self–assembly of BCPs to obtain microphase separated morphologies for different applications. Three representative BCP systems, having lamellar, cylindrical and spherical microdomains are discussed. First, the self–assembly of lamella–forming brush block copolymers (BrBCPs) having polylactide (PLA) and polystyrene (PS) side chains were studied in the bulk and in thin films. The domain size increased approximately linearly with the molecular weight of the backbone, which indicated that the backbone was in an extended conformation that was confirmed theoretically. In situ small angle x–ray scattering (SAXS) measurements indicated that the self–assembly of the BrBCPs was quite rapid, due to the rigid nature of the backbone chain, Second, the directed self–assembly of cylinder–forming polystyrene–block–poly(ethylene oxide)s (PS–b–PEOs) in thin films were investigated. The polymer–surface interactions were tuned by hydroxyl end–functionalized polymers, so that the orientation of the PS–b–PEO microdomains was controlled during thermal annealing. Cylindrical PEO microdomains embedded in a PS matrix orientated normal to the silicon substrates were observed over a wide processing window when the substrates were modified by PS– b–PEO BCPs. PS–b–PEOs with an o–nitrobenzyl ester junction point (PS–hν –PEOs) were used to fabricate nanoscopic dot and line patterns having long–range lateral order. The cylindrical BCP microdomains were oriented perpendicular or parallel to the silicon substrates by varying the solvent annealing conditions. The third BCP system examined in this study was a sphere–forming polystyrene–block–polydimethylsiloxane (PS–b–PDMS). Solvent annealing in N–methyl–2–pyrrolidone was used to direct the self–assembly of the spherical microdomains into high areal density arrays on flat Si substrates, PS modified substrates and lithographically patterned substrates, respectively.

Thesis (Ph. D.)--UCLA, 2009. / Vita. Description based on print version record. Includes bibliographical references (leaves 347-368).

The aim of this project is to develop novel approaches for the detection and characterisation of engineered and other potentially harmful nanoparticles in the air. In particular we wish to distinguish specific nanomaterials from the background atmospheric aerosol to provide a means of measuring human exposure to nanomaterials that may present a risk to health. Ideally, solutions should be practically deployable in the field. The metrics considered for measurement across this project are: size, number, chemical nature and surface area. Two main approaches are chosen to address these requirements: online size selective surface area controlled nucleation, and quantitative assessment of size resolved Raman spectroscopic maps. The first approach is based on the discovery of a different regime type of heterogeneous nucleation. In this case nucleation probability is determined by the surface area of the aerosol rather than the number of nuclei present. A portable DMA has also been developed allowing for the pre-separation of particles according to size in a compact package. Combining this DMA with the novel nucleation technology provides a means of measuring surface area distributions of particles. Finally, a novel Raman spectroscopic methodology is presented for the chemically specific quantification of aerodynamically size selected samples. Particles are first aerodynamically size segregated from the air in a wide size range sampler. These size fractionated samples are analysed by Raman spectroscopy. Imaging analysis is then applied to Raman spatial maps to provide chemically specific quantification against the substrate as a proxy for background aerosol. Analysing this data in combination with the known deposition efficiency of aerosols in the respiratory tract (provided by the sampling method), can then provide a complete exposure measurement approach.

The main purpose of this study is to explore individual and organizational level factors which influence the formation of knowledge and technology transfer links between universities and firms. To this end, three sets of data are collected and analyzed. The first one includes bibliometric data of nanotechnology publications, which are authored by scientists affiliated with Turkish universities. The second one is collected through a questionnaire survey from university-scientists dealing with nanoscale research. The third one is from firms doing nanotechnology R&amp / D through in-depth interviews with high level managers. The analysis of bibliometric data provides an insight to the main actors and characteristics of the nanoscale research in Turkey. This data is also used to identify the population of nano-scientists at Turkish universities. From May 2010 to May 2011, 181 questionnaires were collected from targeted nano-scientists / and 21 firms were interviewed. The collected data was used to investigate the impact of individual and organizational level factors on the proclivity of nanoscientists to engage in knowledge and technology transfer to industry by estimating binary probit models. The results suggest that nano-scientists with relations to industry are those who (i) have high number of patents/patent applications / (ii) do more applied research / (iii) have access to public funds (iv) are well connected to Turkish NST academia / (v) are working in universities which are not the most active ones in nanoscale research / but have nano-equipped laboratories / and support nano-scientists in their relations with industry / and finally (vi) are motivated by commercialization of their research outcomes. On the other hand, qualitative analysis of our data collected through in-depth interviews conducted with firms suggests that social capital and human capital of firms&rsquo / nanotechnology professionals play the key role in knowledge and technology transfer from universities. However, absorptive capacity and business culture are the most important firm level factors which influence university-industry relations. Finally, in the last section of this thesis we discuss some managerial and science, technology and innovation policy implications of the research.

Art conservation and restoration on ancient works are continuously involving new types of technologies. These trends are mostly taking place in Europe, especially Florence because it is the foremost leading city of art restoration, and has the most capable and devoted fresco restorers in Italy. This study contributes to the scholarly discourse of advances in art restoration involving computers and nanotechnology, and promotes the use of technology in the field of art. The crux of the paper focuses on the Brancacci Chapel fresco cycle restoration throughout the span of several years. This project is important to the research of art restoration primarily because it has undergone several different methods of repair. This is probably due to the fact that the chapel was subject to a fire in 1771 t as well as the Florence flood of 1966. This thesis examines the different viewpoints of art scholars regarding the implementation of nanoscicence and computers in the field and sheds light on restorations done on recent works and the incorporation of nanotechnology in American museums.

No description available.