TY - JOUR

T1 - Fully screen‐printed silicon solar cells with local Al‐p+ and n‐type POLO interdigitated back contacts with a VOC of 716 mV and an efficiency of 23%

AU - Haase, Felix

AU - Min, Byungsul

AU - Hollemann, Christina

AU - Krügener, Jan

AU - Brendel, Rolf

AU - Peibst, Robby

N1 - Funding Information: The authors thank the Federal Ministry for Economic Affairs and Energy and the state of Lower Saxony for funding this work. The authors also thank S. Schäfer, C. Kruse, and V. Mertens (all ISFH) for fruitful discussions and M. Berger, A. Christ, A. Raugewitz, R. Winter, M. Pollmann, T. Neubert, D. Sylla, and U. Baumann (all ISFH) and R. Zieseniß (Institute of Electronic Materials and Devices) for sample processing and measuring. We also thank TOYO Aluminium for providing the Al‐paste, Heraeus and Dupont for providing the Ag‐pastes, and LONGI for providing the wafer material.

PY - 2021/4/15

Y1 - 2021/4/15

N2 - We demonstrate the fabrication of a fully screen‐printed p‐type silicon solar cell with local hole‐collecting Al‐alloyed (Al‐p+) contacts with a record open circuit voltage of 716 mV. The solar cell is fabricated by using almost the same process equipment as PERC cells. One of the dominant recombination losses in PERC cells is the recombination in the passivated and in the contacted emitter regions that so far limit the open circuit voltage to values below 700 mV. We eliminate these loss channels by substituting the P‐diffused emitter by a passivating n‐type poly‐Silicon on Oxide (nPOLO) contact. We place this contact on the rear side because of its otherwise strong parasitic absorption. The Al‐p+ contacts are also located at the rear side to avoid front‐side shading. This results in a POLO‐IBC cell structure. The efficiency of the best cell so far is 23.0% with a designated area of 4 cm2 fabricated on a M2‐sized wafer. Scanning electron microscopy reveals an Al‐p+ thickness of less than 3.3 μm and only a few 100 nm at the contact ends, which is less than the 5 μm typically for optimized Al‐p+ contacts. A comparison of measured and simulated current‐voltage curves over a variation of the contact fraction extracts a high saturation current density of the Al‐p+ contact of J0‐Al ‐p+ = 2,250 fA cm−2 for the current screen‐print conditions and Al‐paste causing an absolute efficiency loss of 0.5%abs. The recombination at the AlOx/SiNy surface and the shunt resistance limits the cell by 0.6%abs each.

AB - We demonstrate the fabrication of a fully screen‐printed p‐type silicon solar cell with local hole‐collecting Al‐alloyed (Al‐p+) contacts with a record open circuit voltage of 716 mV. The solar cell is fabricated by using almost the same process equipment as PERC cells. One of the dominant recombination losses in PERC cells is the recombination in the passivated and in the contacted emitter regions that so far limit the open circuit voltage to values below 700 mV. We eliminate these loss channels by substituting the P‐diffused emitter by a passivating n‐type poly‐Silicon on Oxide (nPOLO) contact. We place this contact on the rear side because of its otherwise strong parasitic absorption. The Al‐p+ contacts are also located at the rear side to avoid front‐side shading. This results in a POLO‐IBC cell structure. The efficiency of the best cell so far is 23.0% with a designated area of 4 cm2 fabricated on a M2‐sized wafer. Scanning electron microscopy reveals an Al‐p+ thickness of less than 3.3 μm and only a few 100 nm at the contact ends, which is less than the 5 μm typically for optimized Al‐p+ contacts. A comparison of measured and simulated current‐voltage curves over a variation of the contact fraction extracts a high saturation current density of the Al‐p+ contact of J0‐Al ‐p+ = 2,250 fA cm−2 for the current screen‐print conditions and Al‐paste causing an absolute efficiency loss of 0.5%abs. The recombination at the AlOx/SiNy surface and the shunt resistance limits the cell by 0.6%abs each.

KW - IBC solar cells

KW - local Al-p

KW - passivating contacts

KW - POLO

UR - http://www.scopus.com/inward/record.url?scp=85102009463&partnerID=8YFLogxK

U2 - 10.1002/pip.3399

DO - 10.1002/pip.3399

M3 - Article

VL - 29

SP - 516

EP - 523

JO - Progress in Photovoltaics: Research and Applications

JF - Progress in Photovoltaics: Research and Applications

SN - 1062-7995

IS - 5

ER -