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Date Permissions Signed

8-6-2021

Date of Award

Summer 2021

Document Type

Masters Thesis

Department or Program Affiliation

Chemistry

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Berger, Robert F.

Second Advisor

Kowalczyk, Tim

Third Advisor

Bussell, Mark E.

Abstract

As synthetic chemists and materials scientists increasingly gain the ability to precisely arrange the atoms in solids, computation can provide guiding insight toward designing materials for a variety of applications. This work focuses on two distinct projects: 1) the use of biaxial strain in all crystallographic directions to tune the structural and electronic properties of perovskites for solar energy conversion, and 2) the extension of the concept of single-atom alloys to design stable motifs of multiple catalyst atoms on metal surfaces.

Perovskite solar cells have been shown to have band gap tunability when compressive or tensile-biaxial strain is enacted on the unit cell. Past work has almost exclusively focused on strain perpendicular to a B-X bond axis. In the first part of this thesis, using density functional theory (DFT)-based calculations, we look at how varying the axis of strain can further tune the band gap with biaxial strain ranging from ±2%. We predict that perovskites compounds that exhibit polar distortions (i.e. CsGeX 3 , X=Cl, Br, I) under strain will tend to have more band gap tunability when the axis of strain is rotated (with a band gap range of 0.5 eV) than perovskites with octahedral rotations (i.e. CsPbI 3 ). Our calculations suggest a possible route toward the design of perovskite solar cells that more efficiently capture and convert photons in the solar spectrum.

Single-atom alloys (SAAs) are a relatively new class of solid catalysts with isolated catalytically active atoms at the surface. SAAs have the potential to be more efficient, more selective, and less expensive than pure metal catalysts. The extent to which SAAs can be tuned and optimized has not yet fully been explored. In the second part of this thesis, again using DFT-based calculations, we aim to expand on the concept of SAAs to identify multi-atom motifs comprised of two or more elements on a host metal surface. In the future, we will explore the extent to which these new structures help to lower the activation energies of target reactions.

Type

Text

Publisher

Western Washington University

OCLC Number

1263359681

Subject – LCSH

Perovskite solar cells; Solar energy; Alloys; Catalysis

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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