Absorption spectra of conjugated polymers

Scholes GD, Larsen DS, Fleming GR, Rumbles G, Burn PL (2000) Origin of line broadening in the electronic absorption spectra of conjugated polymers Three-pulse-echo studies of MEH-PPV in toluene. Phys Rev B 61(20) 13670-13678... 

The maxima of the absorption spectra of conjugated polymers are located in the visible wavelength region. 

Fig. 1.5 Absorption spectra of conjugated polymers. Adapted from Shim et al. [8] with permission from Springer.

The optical spectra of conjugated polymers are dominated by an intense absorption due to the electric dipole allowed transition between the highest occupied and the lowest unoccupied electronic states. For solid samples the energy of this transition can lie anywhere between about 0.8 and 4 eV. Data for solid samples are listed in Table 9.1 and for solutions and solid samples in Table 9.2 on page 351. 

The optical absorption and emission spectra of conjugated polymers and oligomers have been reviewed. The optical bandgaps of the conjugated polymers that are organic semiconductors range from 1 to 3.5 eV. The photoluminescence spectra of conjugated... 

A series of metfl-carborane-based n-conjugated polymers (57-60 in Figure 26.23), possessing alternate meta-carborane-p-phenylene-ethynylene sequences, were found to exhibit intense blue light emission in solution. The UV-vis absorption spectra of these polymers indicated the extension of n-coniugation due to the presence of rnem-carborane moieties in the polymer backbone (Kokado et al., 2009b). 

This typically featured shape of absorption spectra in conjugated polymers is called vibronic progression. 

Conjugated boron polymers containing platimnn or palladium atom in the main chain were also prepared by hydroboration polymerization between tetrayne/ metal complex monomers and tripylborane (scheme 16).30 From gel permeation chromatographic analysis [THF, polystyrene (PSt) standards], the number-average molecular weights of the polymers obtained were found to be 9000. The polymers were soluble in common organic solvents such as THF, chloroform, and benzene. The absorption peaks due to tt-tt transition were observed around 390 nm in the UV-vis spectra of these polymers. The fluorescence emission spectra exhibited intense peaks at 490 nm in chloroform. 

Two isomeric naphtho[l,8-fec 4,5-fe c ]dithiophene (syn-NDT) and naph tho[l,8-5c 5,4-5 c Jdi thiophene (anfz -NDT) and their dithienyl derivatives which served as good donor components for molecular-based conductors and conducting polymers were developed. Absorption spectra of 453-457 also provide information on the extent of re-conjugation between... 

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