Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Robert G. Hunsperger, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

Thesis (Ph.D.)--Georgia Institute of Technology, 2008. / Adviser: Ajeet Rohatgi. Includes bibliographical references.

Thesis (M.S. in Space Systems Operations)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): Newman, James H. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Satellite, CubeSat, NPS-SCAT, solar cell tester, Power system, Clyde Space, Spectrolabs, improved triple junction, solar power. Includes bibliographical references (p. 83-85). Also available in print.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, Sept. 2004. / Thesis advisor(s): Sherif Michael. Includes bibliographical references (p. 59-60). Also available online.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, Sept. 2004. / Thesis advisor(s): Sherif Michael. Includes bibliographical references (p. 65-66). Also available online.

Dissertation (Ph.D.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics." Bibliography: leaves 97-100.

Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 112-117). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Despite offering relatively high conversion efficiencies, dye-sensitised solar cells using liquid electrolytes containing either I-/I3 - redox couple or Co2+/Co3+ redox couple suffer from durability problems, such as electrode corrosion and electrolyte leakage. Replacements for liquid electrolytes have been extensively studied, but the efficiencies of the resulting devices remain low. One of the factors that limit the efficiency is the sensitising dye. Large sized hole-transport material results in poor pore-filling and thus leads to a fast back electron recombination that reduces the effective electron diffusion length to few micrometeres. The optimal TiO2 layer thickness (2 μm) for maximal power conversion in solid-state dye-sensitised solar cell is much smaller than the 6-10 μm layer thickness required for quantitative light absorption by many dye molecules. Thus, dyes that can absorb in both visible and near-IR region with high extinction coefficient are needed. In order to achieve this, novel oligomers and ruthenium (II) complexes are designed, synthesized and studied as sensitisers for both liquid state and solid state dye-sensitised solar cells in this thesis. Series of ‘donor-free’ dyes including oligo(3-hexylthiophene) (oligo-3HT) (Chapter 3) and oligo(4,4-dihexyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene) (oligo-CPDTs) (Chapter 4) functionalized with cyanoacrylic end groups are easily synthesized using cross-coupling. They were fully characterised through electrochemical, spectroscopic and computational techniques, showing versatile colour-tuning, as well as outstanding absorption coefficients up to 75000 M-1cm-1. Liquid and solid-state DSSCs device performances are studied and discussed in terms of the dye structures. These dyes are effective sensitisers for liquid-state and solid-state dye-sensitised solar cells, although they do not contain a typical donor group, thus open a new strategy of designing dyes in the future. New dyes containing different azo ligands as an additional chromophore moiety to enhance light harvesting of Ru complexes (Chapter 5) have been prepared using a protection/deprotection strategy that allows for convenient purification. The absorption spectrum of the dyes showed an enhanced light harvesting compared to the N719 dye that lacks the azo ligand and electrochemical study also showed properties suitable for application as sensitisers in DSSCs. Following hydrolysis, the complexes were investigated in DSSCs, with performance investigated using I-V measurements. Poor performance was observed and we attribute this as mostly likely due to poor charge injection due to short excited-state lifetime. Although the application of these current dyes in DSSCs is not feasible due to their poor performance, this study allowed us to determine the positions of the HOMO and LUMO orbitals and correlate it to the π-acidity of the dyes.

Organic donor and acceptor have promised the better future energy technologies to alleviate global energy demand and environmental issues. And nowadays they begin to come true in bulk heterojunction organic solar cells (BHJ OSCs) with advantages of low-cost, light-weight, large-area, flexibility, and with high efficiencies (PCEs) of over 14% for converting solar energy to electricity. Porphyrins are unique potential for artificial photocatalysis but their application in BHJ OSCs are still limited by the PCEs less than 10%. This complicacy comes from their inadequate spectral absorptions and the imperfect morphologies. In this thesis, we devote to chemical modification of acceptor-π-porphyrin-π-acceptor (A-π-Por-π-A) structural molecules to enhance their spectral absorptions and phase-separation functions with fullerene acceptor. Firstly, chemically driving J-aggregates have been studied on the new A-π-Por-π-A porphyrin molecule, which could improve the phase-separation of its blend film with PC71BM and and enhance its performance in BHJ OSCs with PCE up to 8.04%. Secondly, two new benzodithiophene (BDT) π-bridged A-π-Por-π-A molecules have been prepared with complementary absorption between the Soret and Q bands. The devices based on the blend fims of the porphyrin donor and PC71BM acceptor exhibit full spectral photocurrent generation and impressive PCEs up to 7.92%. Thirdly, we further extended the π-conjugation of the above BDT π-brigded A-π-Por-π-A molecules by inserting alkyl chain substituted thiophene derivatives into their backbones, resulting in new porphyrin molecules with UV-visible-near-infraed absorption spectra. Using those porphyrin molecules as donor and PCBM as acceptor, the devices show full spectra photocurrent generatoion and appropriate film morphology, resulting in high PCE up to 8.59%. Besides, photocatalysis is also a new promising technology to generate renewable energy. We herein develop new low-cost and noble-metal-free photocatalysts based on Co(OH)2 modified CdS nanowires and applied them for visible light driven hydrogen production from water-splitting. The optimum H2 production rate reaches 14.43 mmol·h−1·g−1 under (λ ≥ 420 nm) upon visible light irradiation, which is 206 and 3 times larger than that of the pristine CdS NWs and 1 wt% Pt-CdS NWs, respectively. The results indicate the promising application of earth-abundant Co(OH)2 as alternative cocatalysts of noble metals.

The molecular design, synthesis, spectroscopic and photophysical characterization of a new series of organic small molecules and transition metal-containing polymers incorporating different n-conjugated chromophores are discussed. The applications of some of these compounds in bulk heterojunction (BHJ) organic solar cells are also outlined. Chapter 1 contains a brief overview on the background of organic solar cells, their structures and performance in solution-processed organic BHJ devices. Chapter 2 presents the synthetic methodology and characterization of a series of new dipyrrin-based materials and their application in organic solar cells. In this section, four metal-based metallopolymers for organic solar cells have been designed, synthesized and two of them have been fabricated for BHJ organic solar cells. Through the alternation of different metal ions and boron element in the same dipyrrin framework, a series of dipyrrin-based metal complexes and BODIPY-containing compounds have been synthesized. Electrochemical analysis and DFT calculations proved that M4 with BODIPY-based structure is more efficient in optimizing the HOMO-LUMO energy level which further increases the Voc value. A full account of the preparation, characterization, photophysical and thermal properties of a new series of benzo[1,2-b:4,5-b']dithiophene (BDT), cyclopenta[2,1-6:3,4-6']dithiophene (CPT) and triphenylamine (TPA) centered small molecules are presented in chapters 3, 4 and 5, respectively. Different acceptor-donor-acceptor (A-D-A) based materials were prepared and employed in organic solar cells in order enhance the power conversion efficiency (PCE) of the devices. Some of the materials have been found to show higher PCEs of up to 3.91%. Given the excellent solution-processability as well as performance advantage, this work provides us a feasible strategy to develop low-cost and high PCE materials in solar cell applications, which would help small molecular organic solar cells to reach a level of practical applications. In chapter 6, four low-bandgap Pt-containing polymers were synthesized and characterized by a variety of techniques. Among them, the largest λonset of 699 nm in solution and λonset of 736 nm in the thin film of P6 were observed and the corresponding energy gap Eg was estimated to be 1.77 eV and 1.68 eV, respectively. After evaluating these oxidation and reduction potentials, P6 also showed the smallest band gap of 1.65 eV with the corresponding HOMO and LUMO energy levels of -5.17 eV and -3.52 eV, respectively. Also, the molecular weights of these polymers were examined by the GPC method. The highest Mn of 24.0 kDa and Mw of 50.4 kDa with the PDI of 2.10 were observed in P8. Chapter 7 and 8 present the concluding remarks and the experimental details of the work described in Chapters 2-6.