Spin dynamics of bulk and quasi-two-dimensional metal halide based perovskite semiconductors
type: CreativeWork
description: This dissertation presents the ultrafast analysis of the electronic states within solution processed bulk and quasi-two-dimensional (quasi-2d) metal halide perovskites. Specifically, of their spin dependencies on lattice and many-body interactions. Many of these results were obtained in close collaboration with others, as specified throughout the dissertation. First, we report that spin-dependent exciton interactions modify the exciton energy and induce spin depolarisation in the quasi-2d Ruddlesden-Popper hybrid metal-halide perovskite Butylammonium Formamidinium Lead Iodide, BA2FAPBI7. Experiments were carried out jointly between Dr Ravichandran Shivanna and me. For carrier densities above ~1015 cm-3, the room temperature exciton depolarisation rate increases with exciton density, showing that many-body interactions outcompete the precessional motional narrowing spin relaxation that was previously reported for lower carrier densities. Therefore, we observe that room temperature spin lifetimes are largest, ~3.2 ps, at an operating carrier density of ~1015 cm-3. We also demonstrate the dynamic circular dichroism that arises from a photoinduced polarisation in the exciton distribution between total angular momentum states. We rationalise this dichroism by a polarisation-dependent exciton-exciton interaction energy that splits co and counter polarised states by 25 meV. In the second part of the thesis, we analyse spin relaxation at cryogenic temperatures, and investigate how the coupling between excitons and the soft ionic crystal lattice impacts the spin relaxation of exciton states in BA2FAPbI7. Faraday rotation measurements were obtained by Dr Soumen Ghosh and Dr Franco V. A. Camargo in close collaboration with me. We report that photoexcitation with energy in excess of the exciton absorption peak increases the spin lifetime by two orders of magnitude at 77K. Our hypothesis is that such optical control of the spin relaxation mechanism arises from the strong couplin…
abstract: This dissertation presents the ultrafast analysis of the electronic states within solution processed bulk and quasi-two-dimensional (quasi-2d) metal halide perovskites. Specifically, of their spin dependencies on lattice and many-body interactions. Many of these results were obtained in close collaboration with others, as specified throughout the dissertation. First, we report that spin-dependent exciton interactions modify the exciton energy and induce spin depolarisation in the quasi-2d Ruddlesden-Popper hybrid metal-halide perovskite Butylammonium Formamidinium Lead Iodide, BA2FAPBI7. Experiments were carried out jointly between Dr Ravichandran Shivanna and me. For carrier densities above ~1015 cm-3, the room temperature exciton depolarisation rate increases with exciton density, showing that many-body interactions outcompete the precessional motional narrowing spin relaxation that was previously reported for lower carrier densities. Therefore, we observe that room temperature spin lifetimes are largest, ~3.2 ps, at an operating carrier density of ~1015 cm-3. We also demonstrate the dynamic circular dichroism that arises from a photoinduced polarisation in the exciton distribution between total angular momentum states. We rationalise this dichroism by a polarisation-dependent exciton-exciton interaction energy that splits co and counter polarised states by 25 meV. In the second part of the thesis, we analyse spin relaxation at cryogenic temperatures, and investigate how the coupling between excitons and the soft ionic crystal lattice impacts the spin relaxation of exciton states in BA2FAPbI7. Faraday rotation measurements were obtained by Dr Soumen Ghosh and Dr Franco V. A. Camargo in close collaboration with me. We report that photoexcitation with energy in excess of the exciton absorption peak increases the spin lifetime by two orders of magnitude at 77K. Our hypothesis is that such optical control of the spin relaxation mechanism arises from the strong couplin…
author: Bourelle, Sean
language: eng
keywords: 2d material, perovskite, spin, transient absorption, transient grating
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/94fb993b-f372-4393-af4d-7fd70bad65cf/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2022-06-14
date modified: 2026-07-22T22:24:21Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.97241