Light management in thin-film
solar cells
Albert Polman
Center for Nanophotonics
FOM-Institute AMOLF
Amsterdam, The Netherlands
Vanguard
satellite 1958
The first practical solar panel (1954)
Bell Laboratories (1954)
2010
Price per solar Watt vs. installed power
P. Maycock
Solar irradiance on earth
Black dots:
area of solar
panels needed
to generate all
of the worlds primary
energy
(all energy consumed:
electricity, heat, fossil
fuels)
assuming 8%
efficient photovoltaics
Available renewable energy sources
Solar cell basic geometry
Solar cell operation
Effects of Rshunt and Rseries on I-V curve
Ideal IV curve
Low Rsh
Rsh = ∞
Rse = 0
High Rse
Light is poorly absorbed in a thin-film solar cell
Solar spectrum
absorbed in 2 m
thick Si film
“Quantum defect” limits efficiency
Photons are
quantized
energy packets:
Eg(Si)=1.1 eV
A 2 eV photon will
give create max.
1 Volt over the
p-n junction
A 0.5 eV photon
is not absorbed
Triple-junction tandem solar cell
1.5 V
1.0 V
0.5 V
Record efficiency solar cell
Triple-junction tandem solar cell layer geometry
From: Richard King (Spectrolab)
Efficiency limits of different solar cell types (2010)
3-junction tandem
Too expensive
crystal Si wafer
2009:
CdTe thin film cells
costs: < 1 $/W
Too low
efficiency
thin film:
CdTe
poly-Si
amorphous Si
organic/polymer
dye-sensitized
other
Materials resources are limited
Relative abundance of elements vs. atomic nr.
Requirements to construct
1 TW of PV with optically
thick cells at 15% efficiency
Solutions:
1) Earth Abundant
Semiconductors
(Si,Cu2O, Zn3P2, FeS2)
2) Enhance Light
Absorption/reduce
semiconductor
volume
from P.H. Stauffer et al, Rare Earth Elements - Critical
Resources for High Technology, USGS (2002)
Photovoltaic materials production and reserve
base
Si solar cell efficiencies
…
© Ron Tandberg