Environmental Engineering Reference
In-Depth Information
Sun Spectrum
1600
P3HT:PCBM SR
0.3
1200
0.2
800
0.1
400
0
0.0
400
600
800
1000
1200
Wavelength (nm)
Fig. 15 Solar spectrum (dash line) and SR of the P3HT:PCBM polymer blend. Because of the
limited absorption range of the polymeric materials, the SR was minimal beyond 650 nm
Fig. 16 a Molecular structures of polymers in the PTB family; b Onset absorptions (l
onset
) and
relative energy levels of these polymers [
58
]
650 nm, corresponding to a band gap energy (E
g
) of approximately 1.9 eV. In other
words, the P3HT:PCBM polymer blend can harvest only approximately 22 % of all
available photons from solar irradiance [
56
]. Therefore, to ensure the harvesting of
more photons, an important task is extending the absorption region.
The development of low-band-gap (LBG) polymers is a promising approach
toward harvesting long-wavelength photons from solar irradiation. Brabec et al.
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