Bipolaron bands derivatives

Optical measurements upon doping show the characteristic features of polarons and bipolarons i.e. the two sub-gap electronic absorption bands predicted by SSH theory [13]. Voss et al. [110] measured difference spectra obtained upon doping for PPV and some soluble derivatives and found broad electronic features in the mid and near infrared, corresponding to the two subgap transitions associated with the bipolaron state. Doping-induced spectra taken by Voss et al. for a series of PPV derivatives are shown in Fig. lVD-5. Similar results are seen in the doping case for PPy [111], as well as for PT [112]. Vardeny et al. 

Figure IVD-5 Doping-induced spectra for PPV and a series of its derivatives. Note vibrational modes in the mid-IR and bipolaron absorption bands in the near-IR. (Taken...

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