Size-Dependent Electron Transfer and Trapping in Strongly Luminescent Colloidal Gallium Oxide Nanocrystals
Bibliographic record
Abstract
Understanding the mechanisms of defect-related photoluminescence in colloidal transparent conducting oxide nanocrystals is important for the development of new multifunctional nanostructures and devices. Here we report a study of the role of NC size, structure, defects, and surface capping on the photoluminescence energy, efficiency, and dynamics of colloidal γ-Ga 2 O 3 nanocrystals. A strong blue emission (quantum yield ∼25%) is associated with the presence of the vacancy-defect sites, and assigned to the donor–acceptor pair (DAP) recombination. The emission energy and lifetime are generally determined by the donor and acceptor binding energies (which are dependent on the NC structure) and the attractive Coulombic interactions between charged donor and acceptor sites (which are dependent on the defect concentration). Variable temperature photoluminescence measurements reveal that binding energies of the donor and acceptor levels are also size-dependent; in 6.0 ± 1.0 nm γ-Ga 2 O 3 nanocrystals donor binding energy was determined to be 205 meV, increasing by ca. 30 meV in 3.3 ± 0.5 nm nanocrystals. The defect sites on nanocrystal surfaces (OH – or O 2– ) also influence DAP recombination by trapping photogenerated valence band holes. Removal of the surface defect sites by capping ligands (dodecylamine and tri- n -octylphosphine oxide) is shown to eliminate this hole-trapping pathway, enhancing a hole capture by the acceptor sites, and increasing the DAP emission intensity. The results of the mechanistic study of the DAP recombination in this work serve as a useful guideline for introducing and manipulating PL properties in oxide nanostructures by controlling the native defect interactions.
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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) | 0.000 | 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 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".