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In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells

Hematite (α-Fe(2)O(3)) is the most studied artificial oxygen-evolving photo-anode and yet its efficiency limitations and their origin remain unknown. A sub-picosecond reorganisation of the hematite structure has been proposed as the mechanism which dictates carrier lifetimes, energetics and the ulti...

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Autores principales: Pastor, Ernest, Park, Ji-Sang, Steier, Ludmilla, Kim, Sunghyun, Grätzel, Michael, Durrant, James R., Walsh, Aron, Bakulin, Artem A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722133/
https://www.ncbi.nlm.nih.gov/pubmed/31481691
http://dx.doi.org/10.1038/s41467-019-11767-9
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author Pastor, Ernest
Park, Ji-Sang
Steier, Ludmilla
Kim, Sunghyun
Grätzel, Michael
Durrant, James R.
Walsh, Aron
Bakulin, Artem A.
author_facet Pastor, Ernest
Park, Ji-Sang
Steier, Ludmilla
Kim, Sunghyun
Grätzel, Michael
Durrant, James R.
Walsh, Aron
Bakulin, Artem A.
author_sort Pastor, Ernest
collection PubMed
description Hematite (α-Fe(2)O(3)) is the most studied artificial oxygen-evolving photo-anode and yet its efficiency limitations and their origin remain unknown. A sub-picosecond reorganisation of the hematite structure has been proposed as the mechanism which dictates carrier lifetimes, energetics and the ultimate conversion yields. However, the importance of this reorganisation for actual device performance is unclear. Here we report an in situ observation of charge carrier self-localisation in a hematite device, and demonstrate that this process affects recombination losses in photoelectrochemical cells. We apply an ultrafast, device-based optical-control method to resolve the subpicosecond formation of small polarons and estimate their reorganisation energy to be ~0.5 eV. Coherent oscillations in the photocurrent signals indicate that polaron formation may be coupled to specific phonon modes (<100 cm(−1)). Our results bring together spectroscopic and device characterisation approaches to reveal new photophysics of broadly-studied hematite devices.
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spelling pubmed-67221332019-09-05 In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells Pastor, Ernest Park, Ji-Sang Steier, Ludmilla Kim, Sunghyun Grätzel, Michael Durrant, James R. Walsh, Aron Bakulin, Artem A. Nat Commun Article Hematite (α-Fe(2)O(3)) is the most studied artificial oxygen-evolving photo-anode and yet its efficiency limitations and their origin remain unknown. A sub-picosecond reorganisation of the hematite structure has been proposed as the mechanism which dictates carrier lifetimes, energetics and the ultimate conversion yields. However, the importance of this reorganisation for actual device performance is unclear. Here we report an in situ observation of charge carrier self-localisation in a hematite device, and demonstrate that this process affects recombination losses in photoelectrochemical cells. We apply an ultrafast, device-based optical-control method to resolve the subpicosecond formation of small polarons and estimate their reorganisation energy to be ~0.5 eV. Coherent oscillations in the photocurrent signals indicate that polaron formation may be coupled to specific phonon modes (<100 cm(−1)). Our results bring together spectroscopic and device characterisation approaches to reveal new photophysics of broadly-studied hematite devices. Nature Publishing Group UK 2019-09-03 /pmc/articles/PMC6722133/ /pubmed/31481691 http://dx.doi.org/10.1038/s41467-019-11767-9 Text en © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Pastor, Ernest
Park, Ji-Sang
Steier, Ludmilla
Kim, Sunghyun
Grätzel, Michael
Durrant, James R.
Walsh, Aron
Bakulin, Artem A.
In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title_full In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title_fullStr In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title_full_unstemmed In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title_short In situ observation of picosecond polaron self-localisation in α-Fe(2)O(3) photoelectrochemical cells
title_sort in situ observation of picosecond polaron self-localisation in α-fe(2)o(3) photoelectrochemical cells
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722133/
https://www.ncbi.nlm.nih.gov/pubmed/31481691
http://dx.doi.org/10.1038/s41467-019-11767-9
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