Impact of N-substitution of a carbazole unit on molecular packing and charge transport of DPP–carbazole copolymers
Bibliographic record
Abstract
Two diketopyrrolopyrrole (DPP)–carbazole (Cz) based π-conjugated copolymers, PDBTCz-H (P1) and PDBTCz-Me (P2), were designed and synthesized to study the effects of N-substitution of the carbazole unit on the molecular ordering, main chain conjugation, and charge transport properties of these polymers. It was found that the existence of hydrogen bonding interaction between the N–H group in the carbazole unit and the CO group in the DPP unit has a significant impact on the UV absorption, crystallinity, thin film morphology, as well as charge transport characteristics of P1. The hydrogen bonding is a very competitive force with the π–π stacking interaction, leading to the more twisted backbone structure and poorer molecular ordering of P1 in the solid state. Although the crystallinity of the P1 thin films could be somewhat improved by thermal annealing, the polymer main chains of P1 remain rather twisted and less conjugated in comparison with P2. The poorer main chain conjugation of P1 caused by the hydrogen bonding led to a dramatic drop in charge transport performance in organic thin film transistors (OTFTs). The highest hole mobility achieved for P1 is 8.9 × 10−3 cm2 V−1 s−1, which is almost two orders of magnitude lower than that of P2 (0.53 cm2 V−1 s−1).
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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".