The role of the host versus the guest in the electroluminescence degradation of PHOLEDs(Conference Presentation)
Bibliographic record
Abstract
Although the electroluminescence (EL) stability of phosphorescent organic light-emitting devices (PHOLEDs) has long been known to depend on the stability of the phosphorescent guest emitter, we recently found that the host also plays an important role. More specifically, we found that interactions between excitons and polarons to result in molecular aggregation of the host material, a phenomenon that appears to play a significant role in the deterioration in efficiency with electrical aging in these devices. The question of whether it is the guest or the host that plays the more leading role in device stability becomes therefore quite relevant. In this work we present data from a comparative systematic study on various host and guest materials used in PHOLEDs. The host materials include CBP, 26DCzPPy and TAPC, and the guest materials include Ir(ppy)3, Ir(ppy)2(acac), Ir(piq)3 and FIrpic. Changes in EL and time resolved photoluminescence characteristics are used in order to understand the interplay between the host and the guest under various electrical and thermal stress conditions. Results suggest that the host plays a more dominant role in determining PHOLED stability. They also shed some light on the interplay between host and guest materials and the effect on device stability. Results from this work will be presented and analyzed.
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| 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".