Revisiting an Ongoing Debate: What Role Do Surface Groups Play in Silicon Nanocrystal Photoluminescence?
Bibliographic record
Abstract
The origin of photoluminescence (PL) in silicon nanocrystals (SiNCs) remains a subject of considerable debate. Size-dependent PL that supports the quantum confinement model has been proposed by several researchers. On the other hand, SiNC PL arising from surface states that are independent of nanocrystal size has also been shown. This work addresses the origin of surface-functionalized SiNC PL as relating to surface states and the NC size. SiNCs of different sizes (3 and 5 nm diameters) were prepared with three distinct surface chemistries. Steady-state and time-resolved PL measurements were performed at temperatures ranging from 37 to 377 K. Temperature-dependent luminescence consistent with core emission was observed for alkyl-terminated SiNCs, while alkylamine-functionalized SiNCs displayed minimal temperature-dependent luminescence, consistent with a charge-transfer mechanism. Lightly oxidized alkyl SiNCs had similar emission profiles to alkyl SiNCs; however, they showed longer luminescence lifetimes and their luminescence spectrum was shifted to shorter wavelengths than their nonoxidized counterparts. A general mechanism is proposed to explain all three phenomena, suggesting that surface groups play a crucial role in SiNC optical response.
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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 | 0.012 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.008 |
| Scholarly communication | 0.005 | 0.012 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.007 | 0.006 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".