using molecules to capture solar energy timothy schmidt
TRANSCRIPT
![Page 1: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/1.jpg)
![Page 2: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/2.jpg)
Using molecules to capture solar Using molecules to capture solar energyenergy
Timothy SchmidtTimothy Schmidt
![Page 3: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/3.jpg)
The solar spectrum
1000 W/m2
![Page 4: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/4.jpg)
Light is made of photons
hc
E Energy of photon
Planck constantSpeed of light
Wavelength
![Page 5: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/5.jpg)
The solar spectrum
Low energy photons
High energy photons
![Page 6: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/6.jpg)
Electrons absorb photons, get energy
E
electrons
unoccupiedenergy levels
diamond
![Page 7: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/7.jpg)
Electrons absorb photons, get energy
E
electrons
unoccupiedenergy levels
silicon
![Page 8: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/8.jpg)
The solar spectrum
1000 W/m2
![Page 9: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/9.jpg)
single threshold solar cells
~32% max
electrons
unoccupiedenergy levels
V
![Page 10: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/10.jpg)
Shockley-Queisser limit
0.5 1.0 1.5 2.0 2.5
5%
15%
25%
35%
SiGaAs
CdS
a-Si:H
CdTe
Band gap /eV
effici
ency
Ge
6000K sun limit
SQ limit
![Page 11: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/11.jpg)
the 3 generations of solar cell
Single threshold(Shockley-Queisser limit)
ThermodynamicLimit
![Page 12: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/12.jpg)
routes to circumventing Shockley-Queisser limit
• using the low energy photons– upconversion– intermediate band cells
• using all the photon’s energy– downconversion– multiple exciton generation– singlet Fission– hot carrier cells
![Page 13: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/13.jpg)
Electrons have “spin”
Ground state S0 Excited state S1
![Page 14: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/14.jpg)
Electrons have “spin”
Ground state S0 Excited state S1 Excited state T1
![Page 15: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/15.jpg)
Molecular photophysics!
absorption
fluorescence(fast, allowed)
![Page 16: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/16.jpg)
Molecular photophysics!
absorption
Phosphorescence(slow, forbidden)
Intersystem crossing
![Page 17: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/17.jpg)
what is wrong with this picture?
![Page 18: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/18.jpg)
T1
triplet-triplet annihilation (TTA)
S1
emitter
S0
emitter
sensitizer
S0
S1
T1
sensitizer
S0
S1
T1T1
S0
TTA
S1
ISCISC
![Page 19: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/19.jpg)
![Page 20: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/20.jpg)
Up-conversion
cell
Up-conversion unit
Limiting efficiency of an Upconversion cell is about 50%
![Page 21: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/21.jpg)
select a sensitizer
tetrakisquinoxalinoporphyrin palladium (II)
![Page 22: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/22.jpg)
ultrafast photoluminescenceThe compound only fluoresces while in S1 (only 10ps!)
Measured fluorescence lifetime = 5psCalculated fluorescence lifetime = 20nsFluorescence yield = 0.025%Triplet yield may be 99.975%!
![Page 23: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/23.jpg)
select an emitter
100% fluorescence yieldused by others for TTA upconversion
![Page 24: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/24.jpg)
![Page 25: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/25.jpg)
![Page 26: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/26.jpg)
TTA emission kinetics
![Page 27: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/27.jpg)
prompt fluorescence vs upconversion
laserlaser
upconversion fluorescence
![Page 28: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/28.jpg)
TTA yieldsmixture ref pure rubrene ref
33%
25%
![Page 29: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/29.jpg)
Nothing wrong with this picture!
![Page 30: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/30.jpg)
or this…
![Page 31: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/31.jpg)
ummmm?
![Page 32: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/32.jpg)
![Page 33: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/33.jpg)
Dennis Cheng
Dr Nicholas J. Ekins-Daukes(NED)
Now at Imperial Collegeour man in London
Dr Raphael “femtofingers” Clady
Murad Tayebjee
![Page 34: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/34.jpg)
$$ acknowledgements $$
University of SydneyUniversity of NSW
ARC LIEFARC DPGCEP
![Page 35: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/35.jpg)
![Page 36: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/36.jpg)
Application to a-Si
realistic a-Si cell100nm, 200nm or 300nm
1mm up-conversion unit
![Page 37: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/37.jpg)
Application to a-Si
Spectra transmittedthrough cell
Modelled porphyrin absorption spectra
![Page 38: Using molecules to capture solar energy Timothy Schmidt](https://reader035.vdocuments.mx/reader035/viewer/2022062802/56649ecf5503460f94bdc61a/html5/thumbnails/38.jpg)
Application to a-Si
667 Porphyrin
Jsc Voc FF Eff
100nm 88.8 0.838 55.3% 4.1%
200nm 120 0.874 57.6% 6.1%
300nm 136 0.889 58.2% 7.1%
Bare a-Si
Jsc Voc FF Eff
100nm 84.2 0.832 54.8% 3.8%
200nm 114 0.869 57.4% 5.7%
300nm 131 0.884 58.1% 6.8%
780 Porphyrin
Jsc Voc FF Eff
100nm 89.4 0.839 55.4% 4.2%
200nm 122 0.876 57.7% 6.2%
300nm 139 0.891 58.3% 7.4%
Monster porphyrin
Jsc Voc FF Eff
100nm 105 0.859 56.8% 5.1%
200nm 141 0.893 58.4% 7.6%
300nm 160 0.906 58.8% 8.8%
+34%