Thermally stimulated luminescence in π-conjugated polymers containing fluorene and spirobifluorene units

Thermally stimulated luminescence (TSL) is studied experimentally in pi-conjugated polyfluorene (PF) and in a polymer containing polyspirobifluorene (PSBF). A narrow TSL peak, whose maximum is located at 45 K, evidences for a weak energy disorder in PF films. A broader TSL peak, shifted to higher temperatures, indicates stronger intrinsic disorder and, in some cases, occurrence of deep traps in PSBF. The dominant contribution from phosphorescence to the afterglow emission and coexistence of phosphorescence and fluorescence in the TSL signal can be explained by the energy splitting of the singlet and triplet states of geminate pairs in PF and PSBF. (C) 2003 Elsevier Science B.V. All rights reserved.