Date of Award

January 2016

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Judith L. Jenkins

Department Affiliation

Chemistry

Second Advisor

Pei Gao

Department Affiliation

Chemistry

Third Advisor

David D. Cunningham

Department Affiliation

Chemistry

Abstract

Efficient and affordable energy conversion and energy storage technologies are required to meet society’s increasing demands. Semiconductor nanocrystals are particularly attractive materials for solar energy conversion applications, as their tunable optoelectronic properties can be manipulated to both optimize the absorbance of solar photons and to afford desirable electronic properties. Further tunability of binary semiconductor nanocrystal systems can be realized through substitutional doping. However, doping can be difficult, as the dopants can cause significant lattice strain in the host crystals. Lead-doped ZnS nanocrystals are one promising material for the conversion of solar photons into storable fuels such as hydrogen gas. The ZnS conduction band is sufficiently high in energy to reduce protons, and the lead dopants are hypothesized to add filled states in the ZnS band gap, thereby extending the absorbance of the crystals into the visible region. This work details progress towards controllable doping of ZnS nanocrystals with lead cations using modified hot injection procedures. Preliminary results suggest that the temperature of the ZnS reaction matrix, the temperature of the Pb reaction flask, and the mole ratio between Pb and Zn can be used to afford various mixtures of ZnS and PbS nanocrystals with various sizes and optical properties. Spectroscopic data demonstrates synthesis-dependent optical and electronic properties, and high resolution transmission electron micrographs provide structural information.

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