Industrial implementation of 24%-efficient POLO IBC solar cells and future upgrade to 26%-efficient POLO <sup>2</sup> IBC
Bibliographic record
Abstract
IBC solar cells have gained tremendous interest in the PV industry as next-generation technology. ISFH has developed a lean manufacturing process sequence for POLO IBC solar cells applying p-type Cz wafers, an Al-BSF base contact and local PECVD deposition of the SiO x N y /n-type polysilicon emitter through a glass shadow mask. In this paper, we report a new best POLO IBC cell efficiency of 24.5% processed at ISFH on M2 wafer size. In 2024, we started to transfer the POLO IBC process from the ISFH SolarTeC to the Kalyon PV manufacturing line using their M10 sized p-type Ga-doped Cz wafers and cell production tools. With Kalyon PV's wet chemistry and PECVD AlO x /SiN tools good surface passivation is demonstrated by obtaining an iV oc up to 727 mV using textured, rear side polished AlO x /SiN passivated test wafers. Kalyon PV targets to process first M10-sized POLO IBC solar cells till end of 2025. However, the POLO IBC efficiency will be limited to below 25.5% by the carrier recombination at the Al-BSF base contact. To overcome this limitation aiming at n-type poly / p-type polysilicon POLO 2 IBC cell efficiencies beyond 26%, EnPV and ISFH optimized a carrier selective SiO x /p-type polysilicon layer stack yielding a new best median saturation current density J 0 = 4 ± 1 fA/cm 2 using industrial tools for the wet chemically grown SiO x and the in-situ doped p-type polysilicon layer. ISFH is applying the SiO x /p-type polysilicon layer stack to develop a novel industrial processing sequence for the POLO 2 IBC solar cell. We deposit both polysilicon layers in-situ-doped full-area and laser-structure both polysilicon polarities. Using lab-type tools and p-type float zone (FZ) wafers, a small-area POLO 2 IBC solar cell with 25.5% efficiency has been developed at ISFH. Using M2-sized n-type Cz wafers, a novel IBC trench patterning process, and solely industrial processing tools in the ISFH SolarTeC targeting very cost-effective processes for etch barrier formation, laser structuring, and polysilicon etching, we obtain a measured implied V oc = 735 mV of POLO 2 IBC cells processed without metal contacts. Since the polysilicon contacts minimize carrier recombination at metal contacts, the implied V oc value demonstrates the high V oc potential of this promising new POLO 2 IBC manufacturing process thereby indicating a conversion efficiency potential above 26%.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".