TY - JOUR

T1 - Impact of Local Back-Surface-Field Thickness Variation on Performance of PERC Solar Cells

AU - Min, Byungsul

AU - Muller, Matthias

AU - Wolpensinger, Bettina

AU - Fischer, Gerd

AU - Palinginis, Phedon

AU - Neuhaus, Dirk Holger

AU - Brendel, Rolf

N1 - Funding Information: Manuscript received January 18, 2021; revised March 1, 2021 and March 21, 2021; accepted March 22, 2021. Date of publication April 13, 2021; date of current version June 21, 2021. This work was supported by the German Federal Ministry for Economic Affairs and Energy (BMWi) under the acronyms “HE-LENE” and “GENESIS,” under Grant 0325777 and Grant 0324274, respectively. (Corresponding author: Byungsul Min.) Byungsul Min and Bettina Wolpensinger are with the Institute for Solar Energy Research Hamelin, 31860 Emmerthal, Germany (e-mail: min@isfh.de; wolpensinger@isfh.de).

PY - 2021/4/13

Y1 - 2021/4/13

N2 - This article investigates the impact of the back-surface-field (BSF) thickness variation within a local aluminum contact on the performance of passivated emitter and rear contact solar cells. A significant difference of BSF thickness between contact endings and the center of dash-shaped contacts is verified experimentally by a comprehensive statistical analysis using scanning electron microscopy. The impact of local BSF thickness differences on the cell performance is studied with 3-D technology computer-aided design (TCAD) device simulations. Several device parameters such as BSF thicknesses, the doping concentration in the BSF profile at rear contacts, or the metallized area fraction at the cell rear side are varied. Our simulation study shows that the open-circuit voltage is mainly affected by locally reduced BSF thicknesses, resulting in an efficiency loss up to 0.14%abs or 0.84%abs, respectively, if an area fraction of 1% or 20% within a local contact has reduced BSF thicknesses. This effect can be minimized either by reducing the metallized area fraction at the cell rear side or by increasing the doping concentration in the BSF profile at aluminum rear contacts. In addition, we demonstrate that the 3-D simulations can be approximated with 2-D simulations by applying a single doping profile with an average BSF thickness, calculated with the harmonic mean.

AB - This article investigates the impact of the back-surface-field (BSF) thickness variation within a local aluminum contact on the performance of passivated emitter and rear contact solar cells. A significant difference of BSF thickness between contact endings and the center of dash-shaped contacts is verified experimentally by a comprehensive statistical analysis using scanning electron microscopy. The impact of local BSF thickness differences on the cell performance is studied with 3-D technology computer-aided design (TCAD) device simulations. Several device parameters such as BSF thicknesses, the doping concentration in the BSF profile at rear contacts, or the metallized area fraction at the cell rear side are varied. Our simulation study shows that the open-circuit voltage is mainly affected by locally reduced BSF thicknesses, resulting in an efficiency loss up to 0.14%abs or 0.84%abs, respectively, if an area fraction of 1% or 20% within a local contact has reduced BSF thicknesses. This effect can be minimized either by reducing the metallized area fraction at the cell rear side or by increasing the doping concentration in the BSF profile at aluminum rear contacts. In addition, we demonstrate that the 3-D simulations can be approximated with 2-D simulations by applying a single doping profile with an average BSF thickness, calculated with the harmonic mean.

KW - Local back-surface-field (BSF) thickness

KW - open-circuit voltage

KW - passivated emitter and rear cell (PERC) solar cells

UR - http://www.scopus.com/inward/record.url?scp=85104226744&partnerID=8YFLogxK

U2 - 10.1109/JPHOTOV.2021.3068603

DO - 10.1109/JPHOTOV.2021.3068603

M3 - Article

AN - SCOPUS:85104226744

VL - 11

SP - 908

EP - 913

JO - IEEE Journal of Photovoltaics

JF - IEEE Journal of Photovoltaics

SN - 2156-3381

IS - 4

M1 - 9402782

ER -