Freestone, B.G. orcid.org/0000-0003-4436-8598, Smith, J.A. orcid.org/0000-0001-6889-4408, Piana, G. et al. (12 more authors) (2019) Low-dimensional emissive states in non-stoichiometric methylammonium lead halide perovskites. Journal of Materials Chemistry A, 7. pp. 11104-11116. ISSN 2050-7488
Abstract
Mixed-halide perovskites prepared from methylammonium iodide and lead chloride (MAPbI3−xClx) precursors are becoming increasingly well understood, however the effect of non-stoichiometry in this system is still not clear. Here, we create MAPbI3−xClx perovskites from starting mixtures containing an excess of MAI, and study them using a variety of structural and optical probes. Using grazing incidence X-ray scattering (GIWAXS) we demonstrate the existence of non-perovskite structures, and show that addition of hydroiodic acid (HI) also leads to similar low-dimensional phase formation. Photoluminescence spectroscopy performed at cryogenic temperatures indicates the existence of multiple emissive states between 510 nm and 605 nm resulting from a low dimensional phase (LDP) or multiple phases. By mapping the distribution of luminescence across the surface with submicron resolution, we found strong co-localisation of LDP emissive states. At certain blend ratios, emission is seen from both LDP states and methylammonium lead iodide perovskite (around 770 nm). Photoluminescence excitation spectroscopy of mixed-phase films reveals energy transfer, or a cascade, between different LDP states, but this process only occurs inefficiently to the surrounding perovskite. Time-resolved photoluminescence measurements demonstrate that LDP excited-state lifetimes decrease as a function of increasing temperature; a process consistent with a thermally-activated charge transfer process. Our work suggests that non-stoichiometric materials prepared via this processing route can lead to the formation of metastable LDPs with unique material properties that merit further investigation.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry 2019. This is an author-produced version of a paper subsequently published in Journal of Materials Chemistry A. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number EUROPEAN COMMISSION - HORIZON 2020 676108 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 13 May 2019 16:07 |
Last Modified: | 05 Apr 2020 00:38 |
Status: | Published |
Publisher: | Royal Society of Chemistry |
Refereed: | Yes |
Identification Number: | 10.1039/c8ta12184b |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:145964 |