Lifetime study of polymer light-emitting electrochemical cells
Bibliographic record
Abstract
The lifetime and degradation characteristics of frozen-junction polymer light-emitting electrochemical cells have been studied. Two seemingly minor factors, the end group of the same luminescent polymer and the type of substrate on which the device is constructed, have shown profound effects on the stress behaviors of these devices operated at a nominal operating temperature of 200K. In devices made on glass substrates, an anomalous large increase in light intensity and driving voltage has been observed under constant current stress measurement. This has been attributed to the relaxation of the electrochemical doping, which leads to reduced photoluminescence quenching and increased resistance in the polymer film. The doping relaxation is accelerated by the poor thermal conductivity of glass substrate, which causes significant temperature rise in the device due to self-heating. Evidence also suggests that doping relaxation can even occur at below the glass transition temperature of the polymer electrolyte. All devices are shown to be short lived when operated at or above 250K due to fast doping relaxation. However, devices made on sapphire substrates based on 3,5-dimethyl phenyl-terminated poly[5-(2′- ethylhexyloxy)-2-methoxy-1, 4-phenylene vinylene] are remarkably stable when operated at 200K, with an estimated half-life of 700h even when stressed at a very high current density of 1A∕cm2.
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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 | 0.000 | 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".