Baran Group Meeting
Terry Lou
Assessment of a solar cell
Power conversion efficiency (PCE; n)
=
Jsc VocFF
SC
Pin
FF = Pmax(seVoc)
SC
Jsc short-circuit photocurrent density (V=0)
Voc open-circuit photovoltage (J=0)
SC
=
FF
= "fill factor"
P
=
intensity of incident light
Current (mA)
4.0
3.5
55
Dye-Sensitized Solar Cells
3.0
Voc = 0.7210 V
2.5
Imax 3.55 mA
Jsc 20.53 mAcm-2
2.0
Fill Factor
70.41%
1.5
Vmax = 0.546 V
10
1.0
Isc = 3.82 mA
0.5
Pmax 1.94 mW
Efficiency
10.4 %
0.0
-0.5
-0.2
0.0
0.2
0.4
0.6
0.8
Voltage (V)
Dye-sensitized solar cell (aka Grätzel cell)
Invented by Michael Grätzel in 1985
State-of-the-art device reported in 1991 achieved
n = 7.1% at 1 sun; n = 12% in diffuse daylight;
IPCE 97% (520 nm)
Baran Group Meeting
Separate light absorption from charge carrier transport
Composition (n-type)
Working electrode (-ve; anode)
Transparent conducting oxide glass (TCO)
Semiconductor
Photosensitizer (dye)
Jun 5, 2021
==
122°C
Michael Grätzel (1944-)
Professor at EPFL
(Lausanne, CH)
Glass
TCO
TiO2 with dye
in
P = maximum power point
max
Incident photon to converted electron (IPCE) represents quantum efficiency
at a particular wavelength
Standard Conditions: AM 1.5G (1 sun)
(42° angle of elevation of the sun; Irradiance
Shockley-Queisser limit
Maximum n = 33.7% at band gap of 1.34 eV
at AM 1.5G for a single-junction solar cell
-
-
Spectrum losses
Blackbody radiation
Recombination of e-/h+
=
1000 W m-2)
Max Efficiency (%)
30
20
20
10
-
Impedance (resistance; fill factor)
For infinite stack of p-n junctions,
theoretical limit for n = 68.7% (1 sun)
JACS 1985, 107, 2988-2990; Nature 1991, 353, 737-740.
1
2
Bandgap (eV)
Electrolyte
Counter electrode (+ve; cathode)
(Catalyst)
TCO glass
UNI-T
CE
DT830C
3
33
Electrolyte (I/13)
TCO
Glass
2
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