Significant Photostability Enhancement of Inverted Organic Solar Cells by Inserting an N-Annulated Perylene Diimide (PDIN-H) between the ZnO Electron Extraction Layer and the Organic Active Layer
Bibliographic record
Abstract
We investigate the effect of adding an N-annulated perylene diimide dye with a pyrrolic NH functional group (PDIN-H) onto an electron extraction layer (EEL) in a bilayer configuration (ZnO/PDIN-H) on the photostability of inverted organic solar cells (OSCs). To do so, we insert a thin layer of PDIN-H in between the ZnO layer and the bulk heterojunction (BHJ) active layer. Results show that under prolonged ultraviolet (UV) irradiation, the cells with the ZnO/PDIN-H EEL exhibit substantially higher photostability compared to the reference cells with only ZnO, leading to respective T 80 values of ≳780 h versus only ∼124 h, where T 80 is the time before the power conversion efficiency (PCE) decreases to 80% of its initial value. The higher PCE photostability arises primarily from the more stable open-circuit voltage ( V oc ) and fill factor (FF) under UV stress. Changes in the dark reverse current characteristics of the cells show that the higher V oc stability acquired upon adding PDIN-H on top of ZnO is mainly due to the ability of the ITO/ZnO/PDIN-H contact to maintain the blockage of hole injection even after UV stress. Analysis of the voltage dependence of dark and light ideality factors verifies that inserting PDIN-H prevents to a significant extent the UV-induced surface recombination that is observed at the ZnO/active-layer interface, thus enhancing the cells’ photostability. Results from hole-only devices and ultraviolet photoelectron spectroscopy reveal that the passivation of ZnO surface defects by PDIN-H is the primary origin of suppressing the UV-induced surface recombination and thereby increasing the photostability. The findings provide not only critical insights into the substantial role of the electron collection contact in the photodegradation of OSCs but also strategies to control them that can be utilized well beyond the specific material system being studied here.
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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".