Dimensional reduction of halide double perovskites

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Dimensional reduction, or conversion of a three-dimensional (3D) structure to a lower dimensional derivative, can afford dramatic changes in a material's optoelectronic properties. While the effects of dimensional reduction on the family of lead-halide perovskites have long been studied, dimensional reduction of the more compositionally diverse family of halide double perovskites has remained largely unexplored. I investigate the effects of dimensional reduction on two electronically distinct 3D double perovskites, Cs2AgBiBr6 and Cs2AgTlBr6, through the synthesis and characterization of lower-dimensional analogues of mono- and bilayer thickness. These studies reveal that quantum confinement has a much larger effect on the optical properties of the Ag--Tl materials than on their Ag--Bi analogues due to the more delocalized electronic character of the Ag--Tl lattice. Interestingly, electronic structure calculations reveal a substantial change in bandgap symmetry upon dimensional reduction. At the monolayer limit, the indirect bandgap of Cs2AgBiBr6 becomes direct, while the direct bandgap of Cs2AgTlBr6 becomes indirect. To understand these changes, I develop a model to describe and predict the band structures of 2D halide double perovskites based on the atomic orbitals of their constituent elements which reveals the underlying factors that drive the bandgap transitions. Finally, I describe how the increased structural flexibility of the 2D perovskite framework can be used to expand the compositional and functional diversity of the perovskite family through the synthesis of a mixed-valence Cu+--Cu2+--In3+ 2D perovskite. The unusual composition of this material affords optoelectronic properties which are not commonly found in 2D perovskites of monolayer thickness


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 2020; ©2020
Publication date 2020; 2020
Issuance monographic
Language English


Author Connor, Bridget Ann
Degree supervisor Karunadasa, Hemamala
Thesis advisor Karunadasa, Hemamala
Thesis advisor Bao, Zhenan
Thesis advisor Solomon, Edward I
Degree committee member Bao, Zhenan
Degree committee member Solomon, Edward I
Associated with Stanford University, Department of Chemistry.


Genre Theses
Genre Text

Bibliographic information

Statement of responsibility Bridget Ann Connor
Note Submitted to the Department of Chemistry
Thesis Thesis Ph.D. Stanford University 2020
Location electronic resource

Access conditions

© 2020 by Bridget Ann Connor
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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