Intensity Dependent Femtosecond Dynamics in a PBDTTPD-Based Solar Cell Material
Bibliographic record
Abstract
PBDTTPD is a conjugated polymer with high power conversion efficiency if used in organic solar cells together with fullerene derivatives. We have investigated for the first time the excited state dynamics of pristine PBDTTPD thin film as well as the ultrafast evolution of charge carriers in PBDTTPD:PCBM bulk heterojunction blend using femtosecond transient absorption spectroscopy. In the latter, charges appear within the time resolution of the experiment (<100 fs), but clean spectral signatures allowed to directly follow slower ∼1 ps charge separation. Only the slower quenching component competes with exciton-exciton and exciton-charge annihilation, leading to a reduced yield of charge carriers at high laser fluence. Our excellent measuring sensitivity made it possible to reduce pump power to a point where annihilation is quasi suppressed. In this case >80% of charges survive after 1 ns; the rest recombines (most probably geminately) on the 200 ps time scale.
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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) | 0.001 | 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".