Interplay between Through-Space and Through-Bond Electronic Coupling in Singlet Fission
Bibliographic record
Abstract
Singlet fission (SF) is a spin-allowed photophysical process that generates two triplet excited states for one absorbed photon. It therefore has the potential to boost solar cell efficiencies beyond the 33% detailed balance limit. A better understanding of through-space and through-bond electronic coupling in SF, and their interplay, is essential for practical applications of SF materials. We have therefore designed three structurally complex pentacene dimers, two of which contain additional subphthalocyanines (SubPcs). These dimers, on the one hand, provide a continuum of electronic coupling and, on the other hand, mimic the complex situation present in the solid state, where a myriad of different packing interactions exist. Quantum chemical calculations and molecular dynamics simulations helped to shed light on the structure-property relationships of these dimers. We employed both steady-state absorption and emission spectroscopy and transient absorption pump-probe experiments to unravel the excited-state dynamics. The SubPcs complement the characteristics of pentacenes and act as light-harvesting antennae that funnel quantitatively the excitation energy via intramolecular Förster resonance energy transfer to the pentacene dimers to realize panchromatic absorption. The latter are subsequently subject to intramolecular SF ( i -SF). The formation of the correlated triplet-pair 1 (T 1 T 1 ) intermediate occurs with rates and yields that are directly proportional to the interpentacene electronic coupling. In contrast, the yield of uncorrelated triplet excited states (T 1 + T 1 ) is indirectly proportional to the interpentacene electronic coupling. Thus, the three dimers demonstrate the decisive role of electronic coupling in i -SF and how to control it. They serve as textbook examples for the opposing dependencies of formation and decoherence of 1 (T 1 T 1 ) on the electronic coupling.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".