Direct Synthesis of Ultrasmall PbS Nanocrystals Passivated with a Metal-Halide-Perovskite-like Monolayer
Bibliographic record
Abstract
Inorganic shelling is a key strategy to address unwanted, surface-mediated nonradiative pathways in semiconductor nanocrystals. Improved passivation particularly advances the use of the smallest nanocrystals because complex photophysics arise as nanomaterials approach the molecular limit. However, shelling strategies developed for larger/more-robust nanocrystals are not always applicable in this size regime. Herein, we introduce the direct synthesis of ultrasmall (ø < 2 nm) PbS nanocrystals shelled with a range of metal-halide-perovskite-like monolayers by employing the appropriate two-dimensional perovskite as a precursor at the point of nanocrystal growth. These passivated nanocrystals possess improved photoluminescence quantum yields, reduced dynamic spectral red-shifting after photoexcitation, and longer, more-monoexponential photoluminescence dynamics─consistent with a reduction in defect-mediated exciton–phonon coupling. We then apply these shelled, ultrasmall PbS nanocrystals as sensitizers in a triplet-fusion upconversion architecture and observe 2-fold improved triplet yields. This demonstration emphasizes the photophysical benefits realized via our 2D perovskite shelling strategy, which can be applied to other nanocrystals─especially to small particles that are similarly vulnerable to existing strategies for post-synthetic modifications.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.005 | 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".