Acetal- and Aldehyde-Substituted Thiophene-Benzodithiophene Copolymers for Organic Solar Cells
Bibliographic record
Abstract
This study introduces two wide bandgap polymers, PBDTAT and PBDTFT, designed for cost-effective organic solar cells (OSCs). PBDTAT, synthesized through Stille coupling polymerization, features a 3-acetal-substituted thiophene building block, while PBDTFT, with the 3-formyl-substituted thiophene building block, is derived through a simple postpolymerization acetal-to-formyl conversion. The acetal substituents induce significant twisting in the polymer backbone, reducing the highest occupied molecular orbital energy ( E HOMO ) of PBDTAT to −5.55 eV. Conversely, formyl groups have less steric impact, resulting in a more coplanar polymer backbone, and a strong electron-withdrawing effect, significantly lowering the E HOMO of PBDTFT to −5.67 eV. These lowered E HOMO levels contribute to achieving higher open-circuit voltages ( V OC ) of 0.77 and 0.84 V for OSC devices with active layers of PBDTAT:Y6 and PBDTFT:Y6, respectively. Surprisingly, space-charge-limited current hole mobilities of PBDTAT, in neat and blend films with Y6, demonstrate similar or higher mobilities than those of PBDTFT, challenging assumptions about the impact of a significantly twisted backbone in PBDTAT on hole transport. This suggests that introducing controlled backbone twisting could strategically broaden the bandgap and reduce the HOMO energy level without compromising charge transport. Consequently, the OSC devices based on PBDTAT:Y6 can achieve a short-circuit current density ( J SC ) of 24.00 mA/cm 2 . Furthermore, photoluminescence quenching experiments confirm highly efficient hole transfer from the PBDTFT/Y6 interface, despite the small E HOMO offset of only 0.07 eV. This leads to a high J SC of up to 24.20 mA/cm 2 for the PBDTFT:Y6-based devices.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".