Synthesis and Properties of Multi-Triarylamine-Substituted Carbazole-Based Dendrimers with an Oligothiophene Core for Potential Applications in Organic Solar Cells and Light-Emitting Diodes
Bibliographic record
Abstract
In this paper, we report on the synthesis and properties of a novel series of multi-triarylamine-substituted carbazole-based dendrimers G 2 -OTP( n )-G 2 ( n = 2−5) with an oligothiophene core. The length of the oligothiophene core varied from 2 to 5 thiophene units. It was found that both the absorption and fluorescence emission peaks red-shifted with increasing oligothiophene core length. As a result, the power conversion efficiencies of the as-fabricated solar cells using the composite of these dendrimers and PCBM as the photoactive layer increased with increasing oligothiophene core length, from 0.04% for G 2 -DTP-G 2 to 0.13% for G 2 -PTP-G 2 under AM 1.5 simulated solar illumination at an irradiation intensity of 100 mW/cm 2 . After a thermal annealing at 150 °C for 15 min under nitrogen, however, the devices based on the G 2 -DTP-G 2:PCBM blend exhibited the most dramatic improvement and almost best performance, although other devices also showed some improvement. Since only G 2 -DTP-G 2 is the a crystalline material among these four dendrimers, the dramatic improvement of the associated devices after annealing is attributed to the formation of some nanocrystalline structures in the active layer, as indicated by DSC analysis and AFM studies. In addition, we have demonstrated that both G 2 -DTP-G 2 and G 2 -PTP-G 2 can be used as hole-transporting emitters in organic light-emitting diodes (OLEDs) with 1,3,5-tris( N -phenylbenzimidazol-2-yl)benzene (TPBI) as a hole-blocking layer and LiF/Al as the cathode. Because of the low hole injection barrier, the turn-on voltages of the OLED devices were as low as 4 V. G 2 -DTP-G 2 exhibited blue electroluminescence with a maximum luminance of 1660 cd/m 2 at 15.5 V, while G 2 -PTP-G 2 emitted yellow light with a highest luminance of 1000 cd/m 2 at 19 V.
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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) | 0.000 | 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 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".