Solar light trapping in slanted conical-pore photonic crystals
Bibliographic record
Abstract
We show that with only one micron, equivalent bulk thickness, of crystalline silicon, sculpted into the form of a slanted conical-pore photonic crystal and placed on a silver back-reflector, it is possible to attain a maximum achievable photocurrent density (MAPD) of 35.5mA/cm2 from impinging sunlight [1]. This corresponds to absorbing roughly 85% of sunlight in the wavelength range 300-1100nm and exceeds the Lambertian limit suggested by previous “statistical ray trapping” arguments. When the silicon volume is reduced to an equivalent thickness of only 380nm, the MAPD remains as high as 32mA/cm2. This suggests the possibility of very high efficiency, ultra-thin-film silicon solar cells. Our one-micron structure consists of a photonic crystal square lattice constant of 850nm and slightly overlapping inverted cones with upper (base) radius of 500nm and 1600nm cone depth. When the solar cell is packaged with silica (each pore filled with SiO2 and modulation on the top is added), the MAPD in the wavelength range of 400-1100nm becomes 32.6mA/cm2 still higher than the Lambertian 4n2 benchmark of 31.2mA/cm2. Thinner structures are considered by keeping the lattice constant and cone radius fixed but by decreasing the cone depth. The MAPD dependence on the overall depth of nanopores indicates that using roughly half the amount of silicon leads to only about 5% drop in the MAPD. In the near infrared regime light is absorbed within slow group velocity modes, that propagate nearly parallel to the interface and exhibit localized high intensity vortex-like flow in the Poynting vector-field.
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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 | 0.001 |
| 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".