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 A2B′(III)B″(I)X6 (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 (APbX3) 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 Cu2+-doped Cs2SbAgCl6 double perovskites that exhibit dramatic shifts in their bandgaps from ∼2.6 eV (Cs2SbAgCl6, parent) to ∼1 eV (Cu2+-doped Cs2SbAgCl6). Powder X-ray diffraction patterns of the Cu2+-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 133Cs NMR spectroscopy reveals that paramagnetic Cu2+ ions are incorporated within the double perovskite material impacting the 133Cs 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 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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".