PbS Nanocrystals Made with Excess PbCl<sub>2</sub> Have an Intrinsic Shell that Reduces Their Stokes Shift
Bibliographic record
Abstract
The use of excess PbCl 2 in the synthesis of PbS nanocrystals has become a convenient route to produce narrow-line-width infrared emitters. However, these materials have found limited adoption in optoelectronic devices—even compared to PbS nanocrystals prepared with lead oleate. Here, using both transmission electron microscopy and small-angle X-ray scattering, we show that excess PbCl 2 results in larger-diameter PbS nanocrystals for the same excitonic features, which is consistent with the formation of an intrinsic insulating shell. We observe further differences in excess-lead-chloride nanocrystals consistent with a shell, including lattice strain and smaller Stokes shifts for intermediate sizes (⌀: 4.8–6.8 nm) that match the passivation/rigidification predicted for a chloride-terminate surface. Our results clarify and rationalize the divergent properties of PbS nanocrystals prepared using different synthetic methodologies, give guidance for device implementation, and offer a new target for synthetic control.
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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".