Photoluminescence studies of chain interactions in electroluminescent polymers

We present the photophysics of some soluble poly(3-alkylthiophenes) (P3ATs) in fluid solution and in the solid state. We have used quantitative time-resolved and steady-state luminescence spectroscopies to examine the photophysics of these polymers in the different environments. We report data that examine the nature of the excited states in these different media and offer an alternative explanation to the low luminescence quantum efficiency of the P3AT films in terms of a decrease in the natural radiative lifetime of the emitting state. The importance of the solvating alkyl groups will be discussed in terms of the excited state dynamics, the nature of the excited states and the influence on both the solvato - and thermochromic properties of these polymers.