Conjugated polymers spectrum

Figure 9 shows the electronic absorption spectrum of a PTTB film which has undergone extensive but incomplete reaction with bromine in a non-in-situ experiment. The absorption spectrum is that expected for a one-dimensional conjugated polymer. The sharpest absorption edge is at about 1490 nm (o.83 eV) and the absorption maximum is located at 1240 nm (1.0 eV). Thus, this material has a bandgap of about 0.83 eV. Note that two small... 

Spectral Sensitization. One of the limiting factors in plastic solar cells is their mismatch with regard to the solar spectrum. Typically, conjugated polymers like MDMO PPV, used for photovoltaics, have their peak absorption around 500 nrn. This is significantly offset from the maximum in the photo-flux of the sun, which peaks around 700 nm. 

Figure 14 shows the unpolarized absorption spectra of films of polythiophene [124] and its hexamer a-sexithienyl [125]. The hexamer solution spectrum is at almost the same energy. As in Fig. 12a, the oligomer shows structure on its rising edge, and the polymer spectrum is structureless. But in Fig. 14 the absorption thresholds differ by = 0.2 eV only one would then say that conjugation extends in PT over only about six monomers. One could show similar data for many other CPs. 

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