eprintid: 10187328
rev_number: 13
eprint_status: archive
userid: 699
dir: disk0/10/18/73/28
datestamp: 2024-03-15 09:34:29
lastmod: 2024-03-15 09:34:29
status_changed: 2024-03-15 09:34:29
type: thesis
metadata_visibility: show
sword_depositor: 699
creators_name: Kerr, Robin
title: Probing Defect States and Surface Restructuring of Prototypical Solar Materials
ispublished: unpub
divisions: UCL
divisions: B04
divisions: C06
divisions: F56
note: Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
abstract: This thesis examines two important solar material surfaces: rutile TiO2 (011)-2×1 and the hybrid organic-inorganic perovskite CH3NH3 PbBr3. Supported by ultraviolet photoemission spectroscopy, resonant two-photon photoexcitation at the TiO2 (011)-formate interface asserts that formate adsorption stabilises the small polarons residing within TiO2 (011) by ∼0.2 eV, possibly pointing to a reversion of the substrate from a 2×1 to a 1×1 reconstruction as has been observed previously upon water adsorption. In contrast to rutile TiO2 (110), no additional photoexcitation channel is observed. Using X-ray photoemission spectroscopy on in situ cleaved single crystal CH3NH3 PbBr3, water adsorption is found to occur with no threshold. Scanning tunnelling microscopy reveals that the associated restructuring is consistent with the Volmer-Weber model, while ultraviolet photoemission spectroscopy shows an increased band gap state density following water vapour exposure, which is attributed to surface defect formation due to lattice swelling. Finally, resonant photoemission is applied to in situ cleaved CH3NH3 PbBr3 to reveal an alternative photoexcitation pathway equal to the band gap energy. Constant final state analysis using coherent two photon photoemission is proposed as a complementary technique for determining the valence band maxima of semiconductor systems.
date: 2024-02-28
date_type: published
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D
language: eng
primo: open
primo_central: open_green
verified: verified_manual
elements_id: 2247769
lyricists_name: Kerr, Robin
lyricists_id: RMJKE05
actors_name: Kerr, Robin
actors_name: Kalinowski, Damian
actors_id: RMJKE05
actors_id: DKALI47
actors_role: owner
actors_role: impersonator
full_text_status: public
pages: 164
institution: UCL (University College London)
department: Chemistry
thesis_type: Doctoral
citation:        Kerr, Robin;      (2024)    Probing Defect States and Surface Restructuring of Prototypical Solar Materials.                   Doctoral thesis  (Ph.D), UCL (University College London).     Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10187328/7/Kerr_10187328_Thesis.pdf