Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 126-137).

Universiẗat, Diss., 2004--Freiburg (Breisgau). / Erscheinungsjahr an der Haupttitelstelle: 2003.

Wide-bandgap metal halide perovskite solar cells have become an alluring next-generation solar panel technology because of their simple manufacturing and rising efficiencies by up to 25.7%. When the single junction devices face the ultimate S-Q limit, the incorporation of wide-bandgap perovskite materials with low-bandgap absorbers to form multi-junction cells offers a promising route to surpass the theoretical efficiency. Monolithic perovskite-organic tandem cells are appealing among other compositions owing to the combination of the sub-cells advantages: low-cost, flexibility, and solution processing. In this work, we focused on optimizing the hole transporting materials (HTMs) separately for the two components in tandem devices. In the 1.76 eV perovskite subcell, three commonly seen HTMs are selected (2PACz, NiOx and PTAA) to investigate the influence on device performance. An MgF2 interlayer at perovskite/C60 is deposited as passivation to enhance the voltage and overall performance. It is found that 2PACz is most suitable for triple cation FA0.7MA0.15Cs0.15Pb(I0.6Br0.4)3, giving good crystallinity, energy match and absorption with a champion PCE of 16.12%. Then, we performed a similar optimization for ternary PM6: BTP-eC9: PC70BM with MoOx, MoOx/2PACz, and PEDOT: PSS as HTMs, where MoOx/2PACz present the best statistics. Finally, two terminal tandem devices were fabricated based on the two optimized subcells, and a promising efficiency of 23.6% and a Voc of 2.09V were reached free of hysteresis. More passivation methods or perovskite bandgap engineering are expected to further improve the performance and break the record.

<p> A description of the McMaster tandem mass spectrometer is given and the usefulness of this instrument in high sensitivity applications is discussed.</p> <p> The pulse characteristics of the 17 stage Allen type electron multiplier which is used on the two stage mass spectrometer were determined and possible means of achieving an improved response in counting applications are discussed.</p> <p> An ion source of the crucible variety was constructed which made possible the detection of 10^-9 grams of a tin isotope. This source was used to detect sub microgram quantities of an enriched tin sample and was also used for the qualitative analysis of a sample which contained tin extracted from a reactor irradiated fuel rod.</p> / Thesis / Master of Science (MSc)

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[Rh(CO]2Cl]2 has been shown to catalyze sequential, mechanistically- distinct transformations in one pot. Tandem allylic alkylation/cycloisomerization sequences have been developed to access valuable, complex structures from relatively simple substrates. A methodology for the enantioselective conjugate addition of 2-heteroaryl nucleophiles to a variety of Michael acceptors has been developed. This method was used successfully in an ongoing approach to the synthesis of cortistatin A. 10 linear steps have been completed towards the synthesis of cortistatin A, including a highly regioselective propargylation to install a quaternary carbon and a diastereoselective intramolecular Diels-Alder reaction. / text

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The purpose of this study had been to design and test a corona column and an insulating gas distribution system for a small tandem Van de Graaff. The intent of this paper is to describe the gas handling system and to compare experimentally the effects of corona electrode shape on the corona current carried between adjacent sections of the column.

Thesis advisor: Marc L. Snapper / Chapter 1 Bisphosphine monoxides have unique coordinating capabilities with transition metals. Several research groups have independently reported transition metal-catalyzed highly stereoselective reactions by using chiral bisphosphine monoxides as the ligands. A review of recent works in this field is provided in this chapter to showcase the features of this class of ligand. Chapter 2 We have developed a copper-catalyzed borylation method to synthesize α-aminoboronic esters, which are biologically interesting molecules in enzyme inhibitions. Employment of hemiaminal ethers as substrates to in situ generate the corresponding aldimines obviated purification of the unstable aldimines and potential imine-enamine tautomerization. By using a chiral bisphosphine monoxide ligand in our copper-catalyzed borylation conditions, we successfully synthesized a variety of enantioenriched alkyl-substituted α-aminoboronic esters in good yields and with good enantioselectivity. Chapter 3 A ruthenium-catalyzed three-step tandem sequence was established to prepare nitrogen-protected 2,3-dihydroxypyrrolidines and 2,3-dihydroxypiperidines. This tandem sequence includes ring-closing metathesis, olefin isomerization and olefin dihydroxylation, and utilizes the second-generation Grubbs’ catalyst as the initial ruthenium precatalyst. Readily accessible nitrogen-tethered dienes were used as the substrates to prepare the heterocyclic compounds in an efficient fashion. Through optimization, we discovered the optimal conditions for ruthenium-catalyzed dihydroxylation of ene-carbamates and ene-sulfonamides, which were the challenging substrates in the previous methods. / Thesis (PhD) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.