Rare-Earth Substitution of La<sub>3</sub>Si<sub>2</sub>S<sub>8</sub>I for Efficient and Color-Tunable Phosphor Converted White Light Emitting Diodes
Bibliographic record
Abstract
Mixed-anion compounds enable properties to be controlled to a greater degree by chemical substitution than single-anion compounds. La 3 Si 2 S 8 I was investigated as a host to develop phosphors based on solid solutions (La 1– x RE x ) 3 Si 2 S 8 I ( RE = Ce, Pr, Tb, Dy, Ho; x = 0–0.33) and (La 1– x – y Ce x RE y ) 3 Si 2 S 8 I ( RE = Tb, Dy; x, y = 0–0.33) that exhibit wide color tunability and white emission. Upon excitation with a 364 nm UV laser source, the phosphors emit through a down-conversion process over a wide visible color gamut. Depending on the RE 3+ concentration, the spectra featured broad emission (cyan for Ce 3+ ) or sharp 4f–4f emission peaks (red for Ho 3+; green for Tb 3+; cyan-green and red for Pr 3+; yellow and cyan for Dy 3+ ) which can be fine-tuned to a wider gamut. The cosubstituted (La 1– x – y Ce x RE y ) 3 Si 2 S 8 I phosphors showed even more intense photoluminescence and wider color palettes within the cyan to green regions (Ce 3+ –Tb 3+ ) and cool to warm white (Ce 3+ –Dy 3+ ). The photometric parameters were appropriate for backlighting display and near UV-pumped phosphor-converted white light-emitting diodes (pc-wLEDs). Photoluminescence decay profiles follow biexponential behavior with lifetimes ranging from a few ns (for Ce 3+ ) to 3–450 μs (for other RE 3+ ). Most of the optimized phosphors were moderately stable at 80–100 °C before the onset of thermal quenching effects. They gave absolute quantum yields up to 50%, which are favorable for efficient energy conversion. Prototype pc-wLEDs fabricated from a blend of three phosphors or from single-phase phosphors showed promising performance.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".