Electronic, Structural, and Optical Properties of Conjugated Polymers Based on Carbazole, Fluorene, and Borafluorene
Bibliographic record
Abstract
We present a first-principles study of the structural, electronic, and optical properties of four conjugated polymers, poly( p -phenylene) (PPP), poly(2,7-fluorene) (PF), poly(2,7-carbazole) (PC), and poly(2,7-borafluorene) (PBF), and of their isolated constituent molecules. All the calculations were done using density-functional theory (DFT) with a plane-wave basis set, pseudopotentials, and local exchange-correlation energy. Resemblances in the atomic structures of the systems studied allow us to make correspondences between their wave functions near the Fermi energy. The dihedral angles of the polymers under consideration are all similar, varying between 26° and 27°. In agreement with experimental data, we find smaller energy gaps for carbazole and borafluorene compared to biphenyl and fluorene, which is due to differences in the highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) wave functions. However, for the polymers, the experimental gap for PC was found to be almost the same as for PPP and PF. Our calculations explain this experimental observation which is attributed to a change in the ordering of the last two valence bands between carbazole and its polymer. We also find that the energy gap of PBF, which has not been synthesized yet, should be smaller than the minimum energy gaps of the other studied polymers by ≃0.5 eV. The polarizations for the lowest electronic transitions are presented from the analysis of the wave functions' symmetries. We find excellent agreement between the calculated and available experimental data, validating the predictions made.
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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".