Instrumentation. All spectroscopic experiments were performed using 10 mm × 10 mm quartz cells. A Cary 1 or Cary 100 UV-visible spectrometer was used to measure absorption spectra (step size of 1 nm, integration of 0.1 s). A PTI QM-40 spectrofluorimeter was used to measure steadystate fluorescence spectra (step size of 0.5 nm, integration of 0.25 s) using a bandwidth of 1 nm for the excitation and emission monochromators. Samples were excited close to the absorption maxima of OTPh (280 nm), pyrene (335 nm) and P3HT (430 nm). Solutions containing only NaDC (Figure ) were used as control experiments and the absorption and emission spectra for these control samples were subtracted from the spectra for OTPh/NaDC and P3HT/NaDC solutions or gels. The experiments were performed at 25 °C. Time-resolved fluorescence measurements were carried out with an Edinburgh Instruments OB920 single-photon counting system using a 16 nm bandwidth for the emission monochromator.