Electronic Structure of Fullerene Heterodimer in Bulk‐Heterojunction Blends
Bibliographic record
Abstract
To increase performance of organic solar cells, the optimization of the electron‐accepting fullerenes has received less attention. Here, an electronic structure study of a novel covalently linked C60‐C70‐heterodimer in blend with the polymer PCDTBT (poly[9‐(1‐octylnonyl)‐9H‐carbazole‐2,7‐diyl]‐2,5‐thiophenediyl‐2,1,3‐benzothiadiazole‐4,7‐diyl‐2,5‐thiophenediyl) is presented. Upon optical excitation of polymer:heterodimer solid films, the unpaired electron is shared between both C60 and C70 cages. In contrast, in the solution the electron is localized on one half of the dimer. Electronic structure calculations reveal that for the C60‐C70‐heterodimer two nearly isoenergetic minima exist, essentially the cis and trans conformers, which are separated by a thermodynamically accessible rotational barrier. In the cis conformation, the edge‐to‐edge distance between the two cages is ca. 4 Å and an unpaired electron is shared between two dimer halves, while in the trans conformation the separation between the fullerene cages is larger and favors electron localization on one half of the heterodimer. By comparison with the experimental data, it is concluded that the cis conformation is preferable in films, and the trans conformation in solution. Modification of the linking molecular bridge opens the possibility to influence the electronic properties of fullerene dimers, which in turn may have an impact on the charge carrier generation efficiency in solar cells.
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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) | 0.002 | 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".