Bandgap chromophores

Since PDAFs are wide bandgap materials, incorporation of other smaller bandgap chromophores as comonomers or substituents enables tuning of the emission colour due to efficient energy transfer from the fluorene to the other units. Random copolymers of fluorenes with other chromophores are readily prepared by the copolymerisation of the dihalochromophore with a dihalofluorene as exemplified in Scheme 9 for the synthesis of copolymers of dioctylfluorene with perylene dyes (1-5 mol%) [46,47]. 

The redox potentials are expressed in volts. If the excitation energies E° and are expressed in electronvolts, the electronic charge q=l and its symbol is often omitted in eqs. 4.20 and 4.21. The bandgap energies usually lie in the range 1.8-3.2 V, so excitation transforms the redox potency of a chromophore. 

Ti02 To date, almost all applications of molecular excited states in sol-gel processed semiconductors such as Ti02 have been for solar energy conversion. Wide bandgap TCO semiconductors, Eg > 1> eV, do not appreciably absorb visible light, and the incorporation of molecular chromophores allows efficient solar harvesting [253-255, 644,... 

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