Chain-length dependence of the electrochemical properties of conjugated oligofluorenes

Electrochemical properties of monodisperse oligofluorenes (OFn, n = 2 to 7) and corresponding polyfluorene were studied by cyclic and differential pulse voltammetry. In combination with data of UV-vis absorption spectra, a series of linear relations such as the band gap, the oxidation potential, the ionization potential, and the electron affinity with the reciprocal number of the fluorene units (1/n) were deduced. When a chain length of ca. 14 repeat units is reached, a stable structure of about one positive charge per 3.5 repeat units is obtained.