Automated wide-line nuclear quadrupole resonance of mixed-cation lead-halide perovskites
<p>Nuclear quadrupole resonance (NQR), a technique related to nuclear magnetic resonance, is extremely sensitive to local crystal composition and structure. Unfortunately, in disordered materials, this sensitivity also leads to very large linewidths, presenting a technical challenge and requir...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Magnetic Resonance |
| Online Access: | https://mr.copernicus.org/articles/6/143/2025/mr-6-143-2025.pdf |
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| Summary: | <p>Nuclear quadrupole resonance (NQR), a technique related to nuclear magnetic resonance, is extremely sensitive to local crystal composition and structure. Unfortunately, in disordered materials, this sensitivity also leads to very large linewidths, presenting a technical challenge and requiring a serious time investment to get a full spectrum. Here, we describe our newly developed, automated NQR set-up to acquire high-quality wide-line spectra. Using this set-up, we carried out <span class="inline-formula"><sup>127</sup></span>I NQR on three mixed-cation lead-halide perovskites (LHPs) of the form MA<span class="inline-formula"><sub><i>x</i></sub></span>FA<span class="inline-formula"><sub>1−<i>x</i></sub></span>PbI<span class="inline-formula"><sub>3</sub></span> (where MA denotes methylammonium; FA denotes formamidinium; and <span class="inline-formula"><i>x</i> =</span> 0.25, 0.50 and 0.75) at various temperatures. We achieve a signal-to-noise ratio of up to <span class="inline-formula">∼ 400</span> for lineshapes with a full width at half maximum of <span class="inline-formula">∼ 2.5 MHz</span> acquired with a spectral width of 20 MHz in the course of 2–3 d. The spectra, which at least partially exhibit features encoding structural information, are interpreted using a statistical model. This model finds a degree of MA–MA and FA–FA clustering (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.2</mn><mspace linebreak="nobreak" width="0.125em"/><mo>≤</mo><mspace width="0.125em" linebreak="nobreak"/><mi>S</mi><mspace width="0.125em" linebreak="nobreak"/><mo>≤</mo><mspace linebreak="nobreak" width="0.125em"/><mn mathvariant="normal">0.35</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="77pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="3a87b1914cc7526b85faf97a713928fc"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="mr-6-143-2025-ie00001.svg" width="77pt" height="11pt" src="mr-6-143-2025-ie00001.png"/></svg:svg></span></span>). This proof-of-principle for both the wide-line NQR set-up and the statistical model widens the applicability of an underutilised avenue of non-invasive structural research.</p> |
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| ISSN: | 2699-0016 |