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Layered BiOI single crystals capable of detecting low dose rates of X-rays

Abstract:

Detecting low dose rates of X-rays is critical for making safer radiology instruments, but is limited by the absorber materials available. Here, we develop bismuth oxyiodide (BiOI) single crystals into effective X-ray detectors. BiOI features complex lattice dynamics, owing to the ionic character of the lattice and weak van der Waals interactions between layers. Through use of ultrafast spectroscopy, first-principles computations and detailed optical and structural characterisation, we show that photoexcited charge-carriers in BiOI couple to intralayer breathing phonon modes, forming large polarons, thus enabling longer drift lengths for the photoexcited carriers than would be expected if self-trapping occurred. This, combined with the low and stable dark currents and high linear X-ray attenuation coefficients, leads to strong detector performance. High sensitivities reaching 1.1  × 103 μC Gyair−1 cm−2 are achieved, and the lowest dose rate directly measured by the detectors was 22 nGyair s−1. The photophysical principles discussed herein offer new design avenues for novel materials with heavy elements and low-dimensional electronic structures for (opto)electronic applications.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41467-023-38008-4

Authors

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Institution:
University of Oxford
Division:
MPLS
Department:
Chemistry
Sub department:
Inorganic Chemistry
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Chemistry
Sub department:
Inorganic Chemistry
Oxford college:
St John's College
Role:
Author
ORCID:
0000-0002-7675-0065
et al.


Publisher:
Springer Nature
Journal:
Nature Communications More from this journal
Volume:
14
Article number:
2452
Publication date:
2023-04-28
Acceptance date:
2023-04-11
DOI:
EISSN:
2041-1723


Language:
English
Keywords:
Pubs id:
1337162
Local pid:
pubs:1337162
Deposit date:
2023-04-12
ARK identifier:

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