Cu(II)-Doped Cs<sub>2</sub>SbAgCl<sub>6</sub> Double Perovskite: A Lead-Free, Low-Bandgap Material
Bibliographic record
Abstract
Lead-free halide double perovskites with a generic formula of A 2 B′(III)B″(I)X 6 (A and B are cations and X is a halide anion) are being explored as a less toxic, higher thermal- and moisture-stable alternative to well-studied lead halide perovskite (APbX 3 ) solar energy absorbers. However, the absorption profiles of most double perovskites reported to date have larger bandgaps (>2 eV) that are poorly aligned with the solar spectrum, reducing their photoconversion efficiency. Here, we present new heterovalent paramagnetic Cu 2+ -doped Cs 2 SbAgCl 6 double perovskites that exhibit dramatic shifts in their bandgaps from ∼2.6 eV (Cs 2 SbAgCl 6, parent) to ∼1 eV (Cu 2+ -doped Cs 2 SbAgCl 6 ). Powder X-ray diffraction patterns of the Cu 2+ -doped polycrystalline materials indicate long-range crystallinity with nonuniform microstrain in the crystal lattice. To decode the dopant, complementary magnetic resonance spectroscopy techniques, solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR), are used to unravel the complex short- and medium-range structure of these novel double perovskite materials. Variable temperature 133 Cs NMR spectroscopy reveals that paramagnetic Cu 2+ ions are incorporated within the double perovskite material impacting the 133 Cs NMR through a Fermi contact interaction. Finally, a comprehensive stress test of the material’s long-term (up to 365 days) thermal and moisture stability indicates excellent resistance to environmental exposure.
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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".