Exploiting and Inhibiting Ion Migration to Control Luminescence in Halide Perovskites
type: CreativeWork
description: This dissertation describes our study on ion migration-driven optoelectronic and structural changes of hybrid metal halide perovskites under light illumination or electric bias, and methods to exploit or inhibit these ion migration processes by implementation of effective passivation approaches. We first critically review recent studies on the photobrightening effect, which has a strong correlation with the extent of photo-induced ion migration processes, and has a substantial impact on performance and lifetime of the perovskite optoelectronic devices. We highlight the sensitivity of this effect to experimental considerations such as atmosphere, photon energy, photon dose, perovskite composition, and morphology, and resolve apparent contradictions in the literature. We then explore the impact of light illumination on triple-cation lead mixed-halide perovskite films, with substantially enhanced luminescence efficiency observed in these materials. We perform a range of experimental characterisations to understand these changes in photo-physical properties of the perovskite materials under light illumination. Although the brightening effect in halide perovskites has the advantage of achieving high luminescence efficiencies, the bandgap instability arising from ion segregation, particularly in systems with high bromide fractions, prevents the full exploitation of the continuous bandgap tunability in perovskite materials. To this end, we demonstrate a passivation approach using potassium halides to both enhance the luminescence efficiency and inhibit ion segregation in hybrid perovskite films. Through photoelectron spectroscopy, and chemical mapping measurements, we indicate that the passivation effects mainly originate from formation of potassium halide inclusions with higher concentration at the perovskite surface. We also explore the changes in properties of perovskite films when biased with an electric field in an operating light-emitting device architecture. Using a…
abstract: This dissertation describes our study on ion migration-driven optoelectronic and structural changes of hybrid metal halide perovskites under light illumination or electric bias, and methods to exploit or inhibit these ion migration processes by implementation of effective passivation approaches. We first critically review recent studies on the photobrightening effect, which has a strong correlation with the extent of photo-induced ion migration processes, and has a substantial impact on performance and lifetime of the perovskite optoelectronic devices. We highlight the sensitivity of this effect to experimental considerations such as atmosphere, photon energy, photon dose, perovskite composition, and morphology, and resolve apparent contradictions in the literature. We then explore the impact of light illumination on triple-cation lead mixed-halide perovskite films, with substantially enhanced luminescence efficiency observed in these materials. We perform a range of experimental characterisations to understand these changes in photo-physical properties of the perovskite materials under light illumination. Although the brightening effect in halide perovskites has the advantage of achieving high luminescence efficiencies, the bandgap instability arising from ion segregation, particularly in systems with high bromide fractions, prevents the full exploitation of the continuous bandgap tunability in perovskite materials. To this end, we demonstrate a passivation approach using potassium halides to both enhance the luminescence efficiency and inhibit ion segregation in hybrid perovskite films. Through photoelectron spectroscopy, and chemical mapping measurements, we indicate that the passivation effects mainly originate from formation of potassium halide inclusions with higher concentration at the perovskite surface. We also explore the changes in properties of perovskite films when biased with an electric field in an operating light-emitting device architecture. Using a…
author: Andaji Garmaroudi, Zahra
language: eng
keywords: halide perovskites, ion migration, light-emitting diodes, luminescence, passivation
license: https://www.repository.cam.ac.uk/bitstreams/b53e23d3-7afb-4b38-a85c-23c39e39d251/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2020-08-10
date modified: 2026-07-22T22:23:54Z
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.59589