Goldi-ox : mixing metals and valences in halide perovskites
Abstract/Contents
- Abstract
- Throughout my PhD, I have explored and expanded the vast and diverse class of metal-halide perovskites. These extended semiconducting solids can be prepared by aqueous syntheses at near-ambient temperatures and offer myriad applications, the most prominent of which is as high-efficiency solar absorbers in photovoltaic cells. My work has focused on understanding and controlling the optical and electronic effects of combining different metals and distinct oxidation states of the same metal in both known and novel halide perovskites. The perovskite Cs2AgBiBr6 represents one promising nontoxic alternative to the toxic Pb-based perovskites, such as (CH3NH3)PbI3, but it has a large bandgap energy that makes it impractical for use as a high-efficiency single-junction solar absorber. I showed that mixing Sn into Cs2AgBiBr6 reduced the bandgap in a fully nontoxic composition. Using a host of experimental techniques complemented by calculations, I uncovered the structural, electronic, and optical consequences of the complex mechanism of Sn substitution in Cs2AgBiBr6. This study demonstrated the ability to tune the electronic structure of perovskites by mixing metals in a nontoxic composition, opening the door to a wider diversity of methods to manipulate the electronic structures of perovskites. I expanded the family of halide perovskites by discovering and characterizing the new family of gold-cage perovskites, an unprecedented structure with no known analog. This structure, with the general formula Cs8AuIII4MIIIX23 (M = In3+, Sb3+, Bi3+; X = Cl-, Br-, I-), combines zero- and three-dimensional sublattices and features ordering of the homovalent Au3+ and M3+ metals, a rare phenomenon only observed in one other halide perovskite. Furthermore, I demonstrated that the visible light absorption could be tuned across a wide range by changing the M3+ metal and by mixing in Au1+. This work added a new member to the impressive array of halide-perovskite structures and demonstrated tunability of the electronic structure, thereby helping to solidify the promise of studying unique perovskite structures. I further diversified halide perovskites with new structure types that stabilize unusual oxidation states of metals in well-defined mixed-valence solids that are stable to ambient conditions. In addition to rigorously confirming the oxidation state assignments using a slew of characterization techniques, I investigated the optical, electronic transport, and magnetic properties of these unique perovskites. This work expands the small family of mixed-valence 3D halide perovskites to bolster the promise of novel perovskite architectures to incorporate new metals and metals with unusual oxidation states.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Lindquist, Kurt |
|---|---|
| Degree supervisor | Karunadasa, Hemamala |
| Thesis advisor | Karunadasa, Hemamala |
| Thesis advisor | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Thesis advisor | Kanan, Matthew William, 1978- |
| Degree committee member | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Degree committee member | Kanan, Matthew William, 1978- |
| Associated with | Stanford University, Department of Chemistry |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Kurt P. Lindquist. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/yh784qc2541 |
Access conditions
- Copyright
- © 2022 by Kurt Lindquist
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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