TY - GEN
T1 - The effect of rear surface passivation layer thickness on high efficiency solar cells with planar and scattering metal reflectors
AU - Yang, Yang
AU - Mehrvarz, Hamid
AU - Pillai, Supriya
AU - Green, Martin
AU - Kampwerth, Henner
AU - Ho-Baillie, Anita
PY - 2011
Y1 - 2011
N2 - Rear surface reflector of solar cell is designed to improve light
collection capacity by allowing the low energy photons to go through
multiple bounces inside the solar device before escaping. In this paper,
we investigate the thickness effect of rear SiO2 surface
passivation layer on both optical and electrical properties of
front-planar high efficiency PERT (Passivated Emitter and Rear
Totally-Diffused) solar cells. Two kinds of metal reflectors are
fabricated: the conventional planar reflectors by evaporated Al and the
novel scattering reflectors by self assembled Ag nanoparticles. We find
that the thickness dependence of rear SiO2 layer (from 8 nm -
134 nm) on photocurrent shows an asymmetry for planar and scattering
reflectors, moreover, the scattering reflectors perform much better than
the planar reflectors under all tested SiO2 thicknesses. A
maximum current enhancement (calculated from wavelength 900 nm to 1200
nm) of 12.1% is presented for planar reflector with 134 nm SiO2 film, and 18.4% for scattering reflector with the optimized 19 nm rear SiO2
film. Additionally, by adding a detached metal mirror, the maximum
current enhancement from scattering reflector jumps to 27.0%. Effective
optical path length Z is calculated to study the light trapping (optical
properties) under various SiO2 thicknesses for both
reflectors. Diffusion length L is calculated to track the electrical
performance. It is shown that thicker SiO2 is of benefit for
both optical and electrical properties when planar Al reflector is used.
However, for scattering reflectors, thinner SiO2 is preferable for optical enhancement, but thicker SiO2 is desirable for electrical gain. 19 nm SiO2 is found to be the best choice for cells with scattering reflectors, considering both effects.
AB - Rear surface reflector of solar cell is designed to improve light
collection capacity by allowing the low energy photons to go through
multiple bounces inside the solar device before escaping. In this paper,
we investigate the thickness effect of rear SiO2 surface
passivation layer on both optical and electrical properties of
front-planar high efficiency PERT (Passivated Emitter and Rear
Totally-Diffused) solar cells. Two kinds of metal reflectors are
fabricated: the conventional planar reflectors by evaporated Al and the
novel scattering reflectors by self assembled Ag nanoparticles. We find
that the thickness dependence of rear SiO2 layer (from 8 nm -
134 nm) on photocurrent shows an asymmetry for planar and scattering
reflectors, moreover, the scattering reflectors perform much better than
the planar reflectors under all tested SiO2 thicknesses. A
maximum current enhancement (calculated from wavelength 900 nm to 1200
nm) of 12.1% is presented for planar reflector with 134 nm SiO2 film, and 18.4% for scattering reflector with the optimized 19 nm rear SiO2
film. Additionally, by adding a detached metal mirror, the maximum
current enhancement from scattering reflector jumps to 27.0%. Effective
optical path length Z is calculated to study the light trapping (optical
properties) under various SiO2 thicknesses for both
reflectors. Diffusion length L is calculated to track the electrical
performance. It is shown that thicker SiO2 is of benefit for
both optical and electrical properties when planar Al reflector is used.
However, for scattering reflectors, thinner SiO2 is preferable for optical enhancement, but thicker SiO2 is desirable for electrical gain. 19 nm SiO2 is found to be the best choice for cells with scattering reflectors, considering both effects.
UR - http://www.scopus.com/inward/record.url?scp=84869472033&partnerID=8YFLogxK
U2 - 10.1109/PVSC.2012.6317810
DO - 10.1109/PVSC.2012.6317810
M3 - Conference proceeding contribution
SN - 9781467300643
SP - 1172
EP - 1176
BT - 2012 38th IEEE Photovoltaic Specialists Conference
PB - Institute of Electrical and Electronics Engineers (IEEE)
CY - Piscataway, NJ
ER -