Mechanism of the Photodegradation of A-D-A Acceptors for Organic Photovoltaics
Bibliographic record
Abstract
In this work, we elucidate the photodegradation pathway of IT-4F, a benchmark A-D-A type semiconductor for organic photovoltaics. The photoproducts were isolated and shown to be isomers of IT-4F formed via a 6-e electrocyclic reaction between the dicyanomethylene unit and the thiophene ring, followed by a 1,5-sigmatropic hydride shift. Importantly, this photoisomerization is accelerated under inert conditions which is explained by DFT calculations that predict the reaction to occur via the excited triplet state (quenchable by oxygen). Adding controlled amounts of the photocyclized product P1 to PM6:IT-4F bulk heterojunction cells shows a progressive decrease of photocurrent and fill factor attributed to its poorer absorption and charge transport properties. The power conversion efficiency drops from 12% for pure IT-4F to 3% for pure P1 acceptor. This cyclization is a general photodegradation pathway for a series of analogous A-D-A molecules with 1,1-dicyanomethylene-3-indanone termini. However, the rate of the reaction varies widely with the nature of the donor moiety.
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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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".