Photoabsorption enhancement in thin-silicon photovoltaics using opaline photonic crystal back-reflectors
Bibliographic record
Abstract
Two attributes of opaline photonic crystal (PC) back-reflectors optically coupled to thin semiconductor films contribute to enhanced optical absorption in the semiconductor. Namely, (i) the PC back-reflector behaves as a perfect mirror (PM), exhibiting complete reflection over stop-gap frequencies; and (ii) the PC-semiconductor film interface couples incident light into resonant states that propagate along the plane of the film, thereby further enhancing absorption. In order to fully realize these benefits the PC must be placed directly adjacent to the absorbing medium. However, in conventional thin-film silicon photovoltaic (PV) cells this is where a nontransparent back contact is typically located. Herein we perform finite-difference-time-domain (FDTD) based calculations in order to investigate the benefits of utilizing an existing electrically conducting PC, namely a ZnO inverted opal, as the back contact for an a-Si:H PV cell. FDTD calculations show that, under normally incident light, the addition of a ZnO inverted opal back-reflector comprising 12 layers enhances the average absorption in a 300nm thick a-Si:H cell by a factor of 4.7 in the spectral region slightly above the a-Si:H band gap. In comparison, absorption is enhanced by just a factor of 2.3 for the case in which a PM is used as a back-reflector. Considering that the efficiency of commercially available a-Si:H cells is typically ~6% the increased absorption due to a 12layered ZnO inverted opal back-reflector represents a potential increase in the relative efficiency of the a-Si:H cell of more than 10% compared to the case in which the a-Si:H cell is backed by a PM.
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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) | 0.000 | 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) | 0.005 | 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".