Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This thesis describes the design and synthesis of homopolymers and copolymers for tuning surface properties of colloidal semiconductor quantum dots (QDs), and directing QD self-assembly to create well-defined 3D structures in which the spatial organization of QDs and other functional materials (e.g. conjugated polymers) is properly controlled. A common feature of all of the polymers described in this thesis is that they contain multiple pendant anchoring groups such as tertiary amines, pyridines and acrylic acids, which bind strongly to QD surfaces as multidentate ligands. This thesis starts by describing a quantitative analytical method based on size exclusion chromatography (SEC) to characterize the interaction of poly(2-N,N-dimethylaminoethyl methacrylate) (PDMA) with TOPO-coated CdSe QDs. In addition, the separation of polymer-bound QDs from excess free polymer can be scaled up by preparative high-performance liquid chromatography. The second part of this thesis explores a method to disperse CdSe and core/shell CdSe/ZnS QDs into water using a poly(ethylene glycol-b-N,N-dimethylaminoethyl methacrylate) (PEG–b–PDMA) diblock copolymer. Alternatively, statistical copolymers, such as poly(oligoethyleneglycol)-co-PDMA (POEG-co-PDMA) and poly(N,N-dimethylacrylamide)-based statistical copolymers carrying pendant pyridine or imidazole groups play the same role as PEG–b–PDMA for dispersion of the QDs into water. The third part of this thesis describes the synthesis and characterization of a water-soluble pH-responsive PDMA-grafted polythiophene (denoted as PT-g-PDMA). The relatively rigid and extended conformation of the polythiophene backbones provides new opportunity for studying the correlation of between optical responses of conjugated polymers and their conformational transitions. In addition, the favorable interaction between the PDMA arms of PT-g-PDMA and CdSe nanorods allows enhanced interface-compatibility of the nanorods with the polythiophene backbone. The last part of this thesis presents a straightforward and versatile approach to achieving nanoscale co-organization of colloidal QDs (e.g. CdSe, CdSe/ZnS core/shell or PbS QDs) with conjugated polymers (e.g. poly(3-hexylthiphene)) by using polymer micelles of poly(styrene-b-4-vinylpyridine) as the structural motif. The spatially defined organization allows photoinduced excited state interaction between the QDs and poly(3-hexylthiphene) at the micellar interface, reminiscent of structures of light harvesting complexes in nature. This strategy is also applicable to other morphologies of polymer self-assemblies, such as poly(styrene-b-acrylic acid) (PS-b-PAA) vesicles.

This thesis describes the design and synthesis of homopolymers and copolymers for tuning surface properties of colloidal semiconductor quantum dots (QDs), and directing QD self-assembly to create well-defined 3D structures in which the spatial organization of QDs and other functional materials (e.g. conjugated polymers) is properly controlled. A common feature of all of the polymers described in this thesis is that they contain multiple pendant anchoring groups such as tertiary amines, pyridines and acrylic acids, which bind strongly to QD surfaces as multidentate ligands. This thesis starts by describing a quantitative analytical method based on size exclusion chromatography (SEC) to characterize the interaction of poly(2-N,N-dimethylaminoethyl methacrylate) (PDMA) with TOPO-coated CdSe QDs. In addition, the separation of polymer-bound QDs from excess free polymer can be scaled up by preparative high-performance liquid chromatography. The second part of this thesis explores a method to disperse CdSe and core/shell CdSe/ZnS QDs into water using a poly(ethylene glycol-b-N,N-dimethylaminoethyl methacrylate) (PEG–b–PDMA) diblock copolymer. Alternatively, statistical copolymers, such as poly(oligoethyleneglycol)-co-PDMA (POEG-co-PDMA) and poly(N,N-dimethylacrylamide)-based statistical copolymers carrying pendant pyridine or imidazole groups play the same role as PEG–b–PDMA for dispersion of the QDs into water. The third part of this thesis describes the synthesis and characterization of a water-soluble pH-responsive PDMA-grafted polythiophene (denoted as PT-g-PDMA). The relatively rigid and extended conformation of the polythiophene backbones provides new opportunity for studying the correlation of between optical responses of conjugated polymers and their conformational transitions. In addition, the favorable interaction between the PDMA arms of PT-g-PDMA and CdSe nanorods allows enhanced interface-compatibility of the nanorods with the polythiophene backbone. The last part of this thesis presents a straightforward and versatile approach to achieving nanoscale co-organization of colloidal QDs (e.g. CdSe, CdSe/ZnS core/shell or PbS QDs) with conjugated polymers (e.g. poly(3-hexylthiphene)) by using polymer micelles of poly(styrene-b-4-vinylpyridine) as the structural motif. The spatially defined organization allows photoinduced excited state interaction between the QDs and poly(3-hexylthiphene) at the micellar interface, reminiscent of structures of light harvesting complexes in nature. This strategy is also applicable to other morphologies of polymer self-assemblies, such as poly(styrene-b-acrylic acid) (PS-b-PAA) vesicles.

As the device size getting nanoscale, quantum dot structure had become one kind of new method of semiconductor manufacturing technology. In this thesis, two series of self-assembled InN quantum dots were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN thin film, based on sapphire(0001) substrate. GaN thin films were characterized by the reflection high energy electron diffraction (RHEED) and scanning electron microscope (SEM). Samples with smooth epitaxial GaN thin films were obtained. Then, InN quantum dots were grown on epitaxial GaN thin film. We have prepared two series of samples. According to the results of the high resolution X-ray diffractometer (HR-XRD) and RHEED patterns, InN structure can be successfully grown on the GaN thin film surface. First series contained samples with InN layer with different thickness and changes of surface morphology were found with increase of InN layer thickness. The second series contained samples with multiple InN layers of the same thickness. Results of atomic force microscopy (AFM), RHEED patterns and SEM, show that InN quantum dots were grown as Stranski-Krastanow growth mode.

Any object can emit infrared radiation if their temperature higher than 0K.Because of this,the photodetectors for infrared radition is very important in application. First,this paper will introduce the kinds and properties of infrared photodetectors but most important is the quantum dot infrared photodetectors.In second chapter,we use the basic physic concepts and mathematical equations to infer the photocurrent and dark current formula. According to the formula,we can see the relationship between current and quantum dot density,bias,donorconcentration, Temperature. After we get the relationship,we can discuss the detectivity,noise properties, optical gain responstivity, differential photoconductivity. According to our research,the electron will be heated at very high ,bias and make the photoconductivity fairly smooth.Moreover,an increase in the effective temperature can result in the occurrence of the voltage range,where differential photoconductivity, is negative. It is important for a infrared photodetector to have high responsivity,detectivity,high working temperature,low dark current and low noise.Excepting this,to comprise a best infrared photodetector must have a good control on growth condition. Because of this,this paper will discuss the relationship between quantum dot and temperature,GRI time, growth thickness,deposited QD material.Finally,this paper find the best growth condition to form a quantum dot infrared photodetector.

In this thesis, ZnSe self-assembled quantum dots (SAQDs) was grown on GaAs substrate by organic-metal vapor phase epitaxy (OMVPE) with Stranski-Krastanow (S-K) growth mode. The contact-mode atomic force microscopy (AFM) and photoluminescence (PL) are used to measure the surface morphology and optical properties of ZnSe SAQDs, respectively. Experimental data show that the flow rate of H2Se have a significant influence on the relation between the density and the growth temperature of ZnSe SAQDs. At the H2Se flow rate of 25 sccm, the density of ZnSe SAQDs increases up to 3.96¡Ñ108 cm-2 as the growth temperature increase from 140¢J to 380¢J. However, the growth temperature has a negligible effect of the density of ZnSe SAQDs at the flow rate of 30 sccm. At the H2Se flow rate of 40 sccm, the density of ZnSe SAQDs decreases as the growth temperature increases due to the coalescences of SAQDs. Furthermore, a cap layer of ZnS was deposited on ZnSe SAQDs. Experimental data indicate that the increase of the thickness of ZnS cap layer results in blue-shifted emission due to the ZnSe SAQDs experience more biaxial strain. Besides, the ZnS cap layer provides an additional source of carriers, which thermalize to the ZnSe SAQDs before recombination, resulting in a significantly stronger photoluminescence signal. In AFM images, the density of ZnSe SAQDs decreases as the increase of the thickness of ZnS cap layer. In conclusion, we have successfully grown the high density of ZnSe SAQDs on the GaAs substrate and deposit the ZnS cap layer on it. Based on the technique, the multi-quantum dots will be developed in the future.

Thesis (M.S.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science degree in Chemistry." "A thesis entitled"--at head of title. Bibliography: leaves 82-85.

Thesis (Ph.D.) -- University of Texas at Arlington, 2009.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references (leaves 78-84). Available also in a digital version.

Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 121-126).