TY - JOUR

T1 - Optimization of Transparent Passivating Contact for Crystalline Silicon Solar Cells

AU - Kohler, Malte

AU - Finger, Friedhelm

AU - Rau, Uwe

AU - Ding, Kaining

AU - Pomaska, Manuel

AU - Zamchiy, Alexandr

AU - Lambertz, Andreas

AU - Duan, Weiyuan

AU - Lentz, Florian

AU - Li, Shenghao

AU - Smirnov, Vladimir

AU - Kirchartz, Thomas

PY - 2020/1

Y1 - 2020/1

N2 - A highly transparent front contact layer system for crystalline silicon (c-Si) solar cells is investigated and optimized. This contact system consists of a wet-chemically grown silicon tunnel oxide, a hydrogenated microcrystalline silicon carbide [SiO2/μc-SiC:H(n)] prepared by hot-wire chemical vapor deposition (HWCVD), and a sputter-deposited indium doped tin oxide. Because of the exclusive use of very high bandgap materials, this system is more transparent for the solar light than state of the art amorphous (a-Si:H) or polycrystalline silicon contacts. By investigating the electrical conductivity of the μc-SiC:H(n) and the influence of the hot-wire filament temperature on the contact properties, we find that the electrical conductivity of μc-SiC:H(n) can be increased by 12 orders of magnitude to a maximum of 0.9 S/cm due to an increased doping density and crystallite size. This optimization of the electrical conductivity leads to a strong decrease in contact resistivity. Applying this SiO2/μc-SiC:H(n) transparent passivating front side contact to crystalline solar cells with an a-Si:H/c-Si heterojunction back contact we achieve a maximum power conversion efficiency of 21.6% and a short-circuit current density of 39.6 mA/cm2. All devices show superior quantum efficiency in the short wavelength region compared to the reference cells with a-Si:H/c-Si heterojunction front contacts. Furthermore, these transparent passivating contacts operate without any post processing treatments, e.g., forming gas annealing or high-temperature recrystallization.

AB - A highly transparent front contact layer system for crystalline silicon (c-Si) solar cells is investigated and optimized. This contact system consists of a wet-chemically grown silicon tunnel oxide, a hydrogenated microcrystalline silicon carbide [SiO2/μc-SiC:H(n)] prepared by hot-wire chemical vapor deposition (HWCVD), and a sputter-deposited indium doped tin oxide. Because of the exclusive use of very high bandgap materials, this system is more transparent for the solar light than state of the art amorphous (a-Si:H) or polycrystalline silicon contacts. By investigating the electrical conductivity of the μc-SiC:H(n) and the influence of the hot-wire filament temperature on the contact properties, we find that the electrical conductivity of μc-SiC:H(n) can be increased by 12 orders of magnitude to a maximum of 0.9 S/cm due to an increased doping density and crystallite size. This optimization of the electrical conductivity leads to a strong decrease in contact resistivity. Applying this SiO2/μc-SiC:H(n) transparent passivating front side contact to crystalline solar cells with an a-Si:H/c-Si heterojunction back contact we achieve a maximum power conversion efficiency of 21.6% and a short-circuit current density of 39.6 mA/cm2. All devices show superior quantum efficiency in the short wavelength region compared to the reference cells with a-Si:H/c-Si heterojunction front contacts. Furthermore, these transparent passivating contacts operate without any post processing treatments, e.g., forming gas annealing or high-temperature recrystallization.

KW - Passivating contact

KW - photovoltaic cells

KW - selective contact

KW - silicon

KW - silicon carbide

KW - solar cell

KW - transparent passivating contact (TPC)

KW - tunneling

KW - RECOMBINATION

KW - PERC

KW - CHEMICAL-VAPOR-DEPOSITION

KW - OPEN-CIRCUIT VOLTAGE

KW - TEMPERATURES

KW - SURFACE PASSIVATION

KW - JUNCTIONS

KW - FILAMENT

KW - HWCVD

KW - EFFICIENCY

UR - http://www.scopus.com/inward/record.url?scp=85077217714&partnerID=8YFLogxK

U2 - 10.1109/JPHOTOV.2019.2947131

DO - 10.1109/JPHOTOV.2019.2947131

M3 - Article

AN - SCOPUS:85077217714

VL - 10

SP - 46

EP - 53

JO - IEEE Journal of Photovoltaics

JF - IEEE Journal of Photovoltaics

SN - 2156-3381

IS - 1

M1 - 8889659

ER -