High-efficiency back-contact back-junction silicon solar cells
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
In this thesis high-efficiency back-contact back-junction (BC-BJ) silicon solar cells for one-sun applications were studied. The focus was put on the development of a low-cost and industrially feasible manufacturing technology in order to utilize the full cost reduction potential of this elegant cell structure. At the same time the performance of the developed solar cells was investigated in details by experimental work, analytical modeling and numerical device simulations. The complex and costly photolithography masking steps were replaced by techniques which are of low cost and relevant for mass production, such as screen-printing of the masking layers and local laser ablation of the dielectric and silicon layers. The highest solar cell efficiency of 21.1 % (JSC = 38.6 mA/cm^2, VOC = 668 mV, FF = 82.0 %) was achieved on 160 um thick 1 Ohm cm n-type FZ Si with the designated area of 4 cm^2. A detailed study of the loss mechanisms limiting the efficiency of the developed back-contact back-junction silicon solar cell was performed. The reduction of the cell efficiency was determined to be 3.9 %abs. due to recombination processes, 2.0 %abs. due to optical losses, 0.3 %abs. due to series resistance effects and 0.7 %abs. due to electrical shading. The developed model of the loss mechanisms is a powerful tool for the further optimization study of the solar cell structure. Positive effects of the phosphorus doped n+ front surface field (FSF) on the performance of the BC-BJ solar cells were studied in details. These effects are: (i) Surface passivation and passivation stability: The optimal surface passivation was obtained with a deep diffused Gaussian phosphorus FSF doping profile with sheet resistance of 148 Ohm/sq. In contrast to solar cells without the FSF diffusion, the solar cells with the FSF diffusion profile did not show any performance degradation under exposure to UV illumination. (ii) Lateral current transport: The front diffused n+ layer can be seen as a parallel conductor to the lateral base resistance. This way the lateral base resistance losses can be reduced. (iii) Low-illumination performance: The front surface field improves the performance of the BC-BJ solar cells under low illumination intensity. Therefore the BC-BJ cells with FSF seem to be the best ones suited for achieving a high energy yield when also operating under low illumination intensity.
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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 | 0.001 |
| Bibliometrics | 0.005 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.016 | 0.005 |
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 it