First Advisor

Erik Johansson

Date of Publication

Winter 3-14-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.) in Chemistry

Department

Chemistry

Language

English

Subjects

Pyrites, Homoepitaxy, Solar cells, Nanocrystals

DOI

10.15760/etd.6117

Physical Description

1 online resource (xvi, 124 pages)

Abstract

Pyrite (FeS2) has recently attracted significant interest as a photovoltaic material due to its promising optical properties, high photon to electron conversion yield, and low-cost raw materials. However, hopes have been tempered by recent discoveries that suggest the presence of hard to remove bulk sulfur defects. This research was focused on engineering and implementing the crystallization of pyrite from a sulfur rich solution to counteract the material's natural tendency to form bulk sulfur defects. Homoeptiaxial layers and single-crystal samples have been grown from tellurium sulfur melts with an Fe:S ratio of 1:4 using both natural and synthetic substrates. The homoepitaxial layer has been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM), confirming the epitaxial nature of the synthetic FeS2 layer, and X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) to better understand the energetics of the grown materials. Furthermore, epitaxial growth onto natural pyrite, in contrast to substrate etching, was established using sulfur-34 substitution and secondary ion mass spectrometry (SIMS). Growth onto synthetic pyrite was also described. Finally, the photovoltaic properties of homoepitaxial layers of high temperature solution growth pyrite onto a synthetic templating crystal was characterized using electrochemical methods.

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Persistent Identifier

http://archives.pdx.edu/ds/psu/24541

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