Phase Evolution in Methylammonium Tin Halide Perovskites with Variable Temperature Solid-State <sup>119</sup>Sn NMR Spectroscopy
Bibliographic record
Abstract
Hybrid organic–inorganic metal-halide perovskite materials are an emerging class of materials that could profoundly change the optoelectronic and solar absorber research fields and have far-reaching applications. Unfortunately, the leading solar-absorbing candidates are lead-containing materials and suffer from chemical instability, eventually decomposing, resulting in detrimental long-term environmental concerns. A series of nontoxic group 14 Sn(II)-based hybrid organic–inorganic metal-halide perovskites is investigated using variable-temperature solid-state nuclear magnetic resonance (NMR) spectroscopy to examine their unique phases that appear between 150 and 540 K. Each phase of the MASnX3 (MA+ = CH3NH3+ and X– = Cl–, Br–, or I–) series is identified and compared to results from quantum chemical calculations of anionic polyhedron clusters. The analysis of the polyhedra about the Sn center is further related to the measured chemical shift anisotropy present when Sn deviates from octahedral symmetry. We also discuss the rapid degradation of pristine MASnI3 over 2 days studied using in situ 119Sn NMR spectroscopy. Finally, we report on the 1H, 13C, 119Sn, and 207Pb NMR structural properties of a Sn/Pb mixed B-site (MASn0.5Pb0.5I3) perovskite, demonstrating the sensitivity of the chemical shift to B-site substitution.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".