Use of delayed electroluminescence as a tool to investigate the emission mechanism of phosphorescent organic light emitting devices
Bibliographic record
Abstract
Delayed electroluminescence (Delayed EL) measurements are used to investigate the emission mechanism in typical Phosphorescent Organic Light Emitting Devices (PHOLEDs). In this work, emission mechanism of PHOLED based on CBP (4,4'-bis(carbazol-9-yl)biphenyl : Ir(ppy)3 (Tris(2-phenylpyridine)iridium(III)) host:guest system is studied. The technique is used to understand whether the EL emission arises from charge recombination directly on guest sites or from recombination on host material followed by host to guest energy transfer. The results show that the emission mechanism changes with the emission layer (EML) thickness. In the case of devices with a thick EML, strong host triplet-triplet annihilation (TTA) is observed, suggesting the presence of significant energy transfer from host to the guest. For the case of devices with thin EML, on the other hand, host TTA is insignificant, suggesting that direct charge trapping on the guest is the main emission mechanism. The results also show that the thickness of the hole transport layer (HTL) has negligible effect on the emission mechanism of PHOLED, showing that the emission mechanism mainly depends on the EML.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".