Unveiling the TADF Emitters with Apparent Negative Singlet‐Triplet Gaps: Implications for Exciton Harvesting and OLED Performance
Bibliographic record
Abstract
Abstract Intramolecular through‐space charge transfer thermally activated delayed fluorescence (TSCT‐TADF) has attracted much attention recently as it can achieve both small energy splitting and high emission efficiency. However, the relationship of excited states between TSCT and through‐bond charge transfer (TBCT) remains a challenge in the TSCT‐TADF molecules. Herein, three compounds DPS‐m‐bAc, DPS‐p‐bAc, and DPS‐OAc that possess emissive TSCT and/or TBCT states are prepared. Interestingly, a so‐called inverted energy gap is found for both DPS‐m‐bAc and DPS‐p‐bAc in toluene solution, which results from the different charge transfer states of ICThigh and ICTlow, as proved by the detailed transient photoluminescence and calculated results. Intense emission from blue to yellow associated with high photoluminescence quantum yields of 70–100% are measured in doped polymethyl(methacrylate) (PMMA) films. Notably, compound DPS‐m‐bAc achieves the highest reverse intersystem crossing rate constant (kRISC) of over 107 s−1 in a PMMA film, benefiting from close‐lying TSCT and TBCT states. The solution‐processed device with DPS‐m‐bAc displays a maximum external quantum efficiency of 21.7% and a relatively small efficiency roll‐off (EQE of 20.2% @ 100 cd m−2). Overall, this work demonstrates how with judicious emitter engineering, a synergy between different charge transfer excited states, can be achieved, providing an avenue to achieve highly efficient solution‐processed OLEDs.
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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".