Solar power is a clean, renewable source of energy. There is a growing demand for cheap, high efficiency photovoltaic cells. Of the many emerging solar harvesting technologies, a concept that has not been widely explored is that of optical antennas. In 1972 Bailey et al.[1] explored scaling down of antenna technology to match the solar spectrum. A recent review was given by Lukas Novotny et al.[2], in which they outline the major hurdles as being the lack of reliable nano-fabrication and an inability to rectify into the Tera-hertz frequencies band. Presently we aim to fabricate photovoltaic cells that incorporate an array of vertically aligned metallic nano-rods (MNR). Porous aluminum oxide (PAO) is used as a nano-structured template for growth of the MNR. PAO exhibit vertically aligned pores (D = 20 - 200nm) in a densely packed hexagonal arrangement. MNR fabrication is achieved through templated electrochemical deposition, and investigated with SEM and VIS-IR spectroscopy. MNR samples have been specifically designed to be incorporated as a photoactive material for a novel photovoltaic cell. Through fine control of their length, the MNR excitation energy can be tuned to the visible spectrum. Excitation of the MNR leads to energy transfer with localized acceptor molecules, creating a rectification of the field. The fabrication of MNR helps progress the development of the proposed antenna photovoltaic device. [1] R. L. Bailey, “A Proposed New Concept for a Solar-Energy Converter," Journal of Engineering for Power, pp. 73-77, Apr. 1972. [2] P. Bharadwaj, B. Deutsch, and L. Novotny, “Optical Antennas," Advances in Optics and Photonics, vol. 1, pp. 438-483, May 2009. / Thesis (Master, Chemistry) -- Queen's University, 2013-01-07 12:36:57.17

In this article, we report the study of defects between single and bulk GaN nanorods in temperature dependence. High quality of GaN nanorods have been investigated by £g-photoluminescence. Optical properties and surface morphology have been analyzed by a series of measurements, including field-emission electron microscopy (FESEM), and cathodoluminescence (CL). CL data reveal that the intensity of surface state emission is larger than near-band-edge emission at 20K . The 3.21eV peak reveals the structural defect at GaN/Si interface. The surface state emission from bottom is larger than top.

In this study, P3HT and PCBM were used as donor and acceptor materials for polymer solar cells. The standard device was constructed of ITO / PEDOT:PSS / P3HT:PCBM / Al and the power conversion efficiency of 2% was achieved under AM1.5G 100mW/cm2 illumination. In order to increase the hole transporting ability, we used PEDOT nanorods with high conductivity as an anode interlayer between the PEDOT:PSS and the P3HT:PCBM layer, with a configuration of ITO / PEDOT:PSS / PEDOT nanorods / P3HT:PCBM / Al. According to experimental results. PEDOT nanorods dispersed well on the PEDOT:PSS surface through the spin-coating process. As the concentration of PEDOT nanorods 1wt% casting film, the conductivity of anode buffer layer raised about two times and the power conversion efficiency of device reached 2.63%. The short-circuit current and the power conversion efficiency of the polymer solar cell containing 1wt% PEDOT nanorods were obtained about 170% and 30% increasement, respectively. In conclusion, it is quite useful to apply the PEDOT nanorods into polymer solar cells as an interlayer. The improvement in the short-circuit current which resulted in an enhancement of the power conversion efficiency originated from the increased conductivity of the buffer layer.

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Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The work presented in this thesis throws light on the supramolecular approach in exploration of bi-porphyrin nanorods system wherein self-assembly plays an important role. Porphyrin based nanorods were synthesized via self-assembly of meso-tetrakis (4-phenylsulfonicacid) porphyrin dihydrochloride and Sn (IV) tetrakis (4-pyridyl) porphyrin. Understanding the sizes and growth mechanism of the porphyrin nanorods by self-assembly and molecular recognition is essential for their successful implementation in nanodevices. Spectroscopic and microscopic studies were carried out to investigate the effect that time, concentration and solvents have on the fabrication of the porphyrin nanorods by ionic self- assembly. This study demonstrated that aggregates of the di- acid form of meso-tetrakis (4-phenylsulfonic acid) porphyrin dihydrochloride and Sn (IV) tetrakis (4-pyridyl) porphyrin resulted in porphyrin nanorods with diameters between 20 nm and 60 nm, and μm in lengths. Enhanced optical properties illustrated the potential for slightly modifying the method of synthesis to influence the physical and optical properties of porphyrin nanorods. The porphyrin nanorods reflectance data demonstrated that these structures are good absorbers of light and therefore could potentially be used to harvest light. The nonlinear optical (NLO) properties of the porphyrin nanorods were investigated for the first time in this study by second and third harmonic generation techniques. Such study was influenced by the fact that porphyrins have great thermal stability and extended -conjugated macro cyclic ring which give them large nonlinear optical effects. The NLO results showed that the porphyrin nanorods may have many potential uses in photonic applications due to larger third order nonlinear susceptibility. Single molecule spectroscopy was also used to investigate the dynamics of intermolecular and intramolecular processes. Porphyrin nanorods were incorporated into polymer matrices to achieve an arrangement where they can be directly used as a device. The assembly of porphyrin nanorods on track-etched membranes was achieved through altering the surface charge of the respective membranes. Porphyrin nanorods-polymer composites were produced using latex technology and electrospinning techniques. The fibres were characterized with respect to morphology and optical properties. / AFRIKAANSE OPSOMMING: Die werk wat in hierdie tesis beskryf word werp lig op die supramolekulêre benadering in die ondersoek van bi-porfirien nano-silinders waarin self-versameling ‘n belangrike rol speel. Porifirien nano-silinders was voorberei via self-versameling van meso-tetrakis(4-feniel sulfoonsuur) porfirien dihidrochloried en Sn (IV) terakis (4-piridiel) porfirien. Dit is belangrik om die meganismes wat verband hou met die groei en grootte van die nano-silinder struktuur te ondersoek. Dit het ‘n invloed op die self-versameling asook die uiteindelike toepassing. Spectroskopiese en mikroskopiese studies was uitgevoer om die effek van tyd, konsentrasie en oplosmiddel op die selfversamelling te bestudeer. Die studie dui daarop dat bondels van die disuur vorm van meso-tetrakis(4-feniel sulfoonsuur) porfirien dihidrochloried en Sn (IV) terakis (4-piridiel) porfirien het gelei tot porfirien nano-silinders met lengtes tussen 20 nm en 60 nm asook in die mikro meter skaal. Verhoogde optiese eienskappe het die potensiaal om effense veranderinge in die metode om die nano-silinders voor te berei om sodoende ‘n groter invloed op die fisiese en optiese einskappe te hê. Die reflektansie data wys dat hierdie strukture goeie absorbsies van lig toon en daarom geskik sal wees om lig te stoor. Die nie-liniêre optisie (NLO) eienskappe van die profirien nano-silinders was vir die eerste keer ondersoek deur middel van tweed en derde hormoniese generasie tegnieke. Hierdie studie was beïnvloed deur die feit dat porfiriene goeie stabiliteit by hoë temperatuur en ‘n verlengde -gekonjugeerde makro-sikliese ring bevat wat dan groot nie-liniêre optiese effekte gee. Die NLO resultate wys dat die profirien nano-silinders groot potensiaal het in die gebruik van fotoniese toepassings as gevolg van derde orde nie-liniêre vatbaarheid. Enkel molekuul spektroskopie was ook gebruik om die dinamika van intermolekulêre en intramolekulêre prosesse te ondersoek. Porfirien nano-silinders was geïnkorporeer in polimeer matrikse om ‘n eweredige verspreiding te verkry en om direk as ‘n toestel te gebruik. Die versameling van porfirien nano-silinders op baan-ingeëtse membrane was bereik deur die verandering in oppervlak lading van die membrane. Porfirien nano-silinder / polimeer samestellings was verkry deur lateks tegnologie en elektrospin tegnieke. Die vesels was gekarakteriseer in terme van morfologie en optiese eienskappe.

>Magister Scientiae - MSc / Cancer is one of the leading causes of death, worldwide. Mortality tolls are estimated to reach approximately 13.1 million in 2030. These statistics suggest that current therapeutic strategies are not effective. This is partly due to the fact that the drugs used in the treatment of cancer lack selectivity and specificity, which lead to undesirable side effects and reduced drug efficacy. There is therefore a need for alternative therapeutic approaches. In view of this, the therapeutic goal of chemotherapy has shifted towards targeted drug delivery systems, which have been successfully demonstrated using nanotechnology. The nano-based drug delivery vehicles that specifically target diseased cells are appealing as they could reduce drug toxicity towards healthy tissues and be more effective at lower dosages. The main aim of this study was to develop gold nanorods (AuNRs) capable of inducing cell death in cancer cells specifically. Selectivity of the AuNRs (denoted as AGK) for cancer cells was achieved by conjugating the AuNRs to a peptide (Adipose Homing Peptide or AHP) that has high affinity and specificity for a cell surface receptor (prohibitin or PHB) that is expressed on some cancer cells. Cell death was achieved through conjugating the AuNRs to a pro-apoptotic peptide, D(KLAKLAK)2. Spherical AuNPs (AuNSs) conjugated with AHP and D(KLAKLAK)2, capable of selectively inducing apoptosis in cancer cells that express PHB, was previously reported. However, in this study the AuNSs were replaced with AuNRs. AuNRs has the ability to absorb light in the near infrared (NIR) light spectrum and converts this light energy into heat. This property of AuNRs has been used in several studies to demonstrate the application of AuNRs for the treatment of cancer using photothermal therapy (PTT). Consequently, the AuNRs described in this study can also be used for PTT. These AuNRs can induce cell death through the target specific delivery of the pro-apoptotic peptide D(KLAKLAK)2 as well as through PTT. The study showed that three human cancer cell lines (PC-3, Caco-2 and U-87) express PHB. The cytotoxicity testing of AGK AuNPs on PC-3 cells showed that these AuNRs could induce apoptosis in these cells without exposure to a NIR light source. The study also shows that AuNRs conjugated with the targeting peptide only (denoted as AG) can induce cell death in Caco-2 through PTT. This study demonstrates the potential of the AuNRs described in this study for application in the targeted elimination of cancer cells through the selective induction of PTT and apoptosis.

Quantum dots and nanorods are becoming increasingly important structures due to their potential applications that range from photovoltaic devices to medicine. The majority of the research on carrier dynamics in these structures has been in the optical regime, with little work performed at Terahertz frequencies where excitonic dynamics can be more directly probed. In this work, we examine theoretically the interaction of Terahertz radiation with colloidal CdSe nanorods to determine the dynamics of excitons generated via a short optical pulse. We calculate the energies and wavefunctions for the excitons within the envelope function approximation in the low density limit where there is at most one exciton per nanorod. The linear Terahertz transmittance and absorbance is found for nanorods that are approximately 70 nm in length and 7 nm in diameter and are compared with experimental results that have shown the first observation of intra-excitonic transitions in nanorods. We find absorbance peaks at 8.5 THz and 11 THz that result from polarizations in the longitudinal (rod axis) and transverse directions respectively. Our theoretical results show that the 8.5 THz and 11 Thz peaks are due to 1s-2pz and 1s-2px transitions respectively. The theoretical absorbance spectra is in good agreement with the experimental one and show that only the ground state is significantly populated 1 ps after optical excitation. This provides strong evidence of rapid trapping of excited holes into the ligand used to passivate the nanorods. A full set of dynamical equations were then constructed from Heisenberg's equation of motion, and were used to model the excitonic correlations as a function of time. Transmittance and absorbance were calculated for different nanorod orientations and electric field strengths in both the linear and nonlinear regime. These results were then averaged over nanorod orientation in order to more accurately reflect experimental conditions. Nonlinearity was found to become significant at peak pulse field strengths of 7 kV/cm and greater. Due to two-photon processes, we predict the 2pz-3dz transition that is not observed in the linear regime will be clearly seen in the nonlinear absorbance spectrum. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-05-14 23:37:58.604

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 86-99).

Diabetes is a disease that causes many complications in human normal function. This disease represents the sixth-leading cause of death in USA. Prevention of diabetes-related complications can be accomplished through tight control of glucose levels in blood. In the last decades many different glucose sensors have been developed, however, none of them are really non invasive. Herein, we present the study of the application of gold and silver nanoparticles with different shapes and aspect ratios to detect glucose traces in human fluids such as tears and sweat. This is to our knowledge the first truly non invasive glucose optical sensor, with extraordinary limit of detection and selectivity. The best proven nanoparticles for this application were gold nanospheres. Gold nanospheres were synthesized using chloroauric acid tri-hydrated (HAuCl4.3H2O) in solution, in the presence of glucose and ammonia hydroxide. The higher the glucose concentration, the higher the number of nanoparticles generated, thus the higher the extinction efficiency of the solution. The linear dependence of the extinction efficiency of the gold nanoparticles solution with glucose concentration makes of this new sensor suitable for direct applications in biomedical sensing. Our approach is based on the well known Tollens test.