Investigating the Tetragonal‐to‐Orthorhombic Phase Transition of Methylammonium Lead Iodide Single Crystals by Detailed Photoluminescence Analysis
Bibliographic record
Abstract
Abstract Here, the phase‐transition from tetragonal to orthorhombic crystal structure of the halide perovskite methylammonium lead iodide single crystal is investigated. Temperature dependent photoluminescence (PL) measurements in the temperature range between 165 and 100 K show complex PL spectra where in total five different PL peaks can be identified. All observed PL features can be assigned to different optical effects from the two crystal phases using detailed PL analyses. This allows to quantify the fraction of tetragonal phase that still occurs below the phase transition temperature. It is found that at 150 K, 0.015% tetragonal phase remain, and PL signatures are observed from quantum confined tetragonal domains, suggesting their size to be about 7–15 nm down to 120 K. The tetragonal inclusions also exhibit an increased Urbach Energy, implying a high degree of structural disorder. The results first illustrate how a careful analysis of the PL can serve to deduce structural information, and second, how structural deviations in halide perovskites have a significant impact on the optoelectronic properties of this promising class of semiconductors.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".