Excited state dynamics of a conformationally disordered conjugated polymer: A comparison of solutions and film

Photo- and electroluminescence in a series of PPV type terpolymers containing fluorene, thiophene and phenylene units

“…However, differently from solutions, this decay is much faster, suggesting that this polymer in solid state is undergoing some kind of quenching process [39,40]. As the emission wavelength is red-shifted to 562 nm, the decay becomes biexponential with a faster component with 1PL = 1.46 ± 0.08 ns (88%) and a longer component with 2PL = 7.9 ± 0.9 ns (12%).…”

Charge transfer relaxation in donor–acceptor type conjugated materials

“…When designing new materials and devices, it is therefore extremely important to understand this relaxation and to account for its effects on the wanted phenomena. Although relaxation in conjugated molecules has been intensely investigated, [20][21][22][23][24][25][26] the implication on device functioning has only been little discussed.…”

“…30 For conjugated polymers in general, the observed <200 fs red shi of the emission spectrum and loss of polarization memory are ascribed to complex electronic and conformational changes leading to dynamic localization of the excited state. 24,25,[39][40][41] Scholes et al have recently shown using two-dimensional electronic spectroscopy that for PCDTBT there is additionally an increase in the excited state charge transfer character during ultrafast relaxation. 20 This signicant phenomenon is however difficult to investigate in detail and using more conventional techniques, because of the limited polymer solubility (preventing solvent-dependent studies) and the experimentally rather inaccessible $200 fs time scale.…”

“…Delocalization in the excited state, even if very short-lived before self-localization, 24,25,[39][40][41] allows us to sample a greater spatial extent of the bulk heterojunction and can help to reach a fullerene interface for charge separation on the ultrafast time scale. 29,63,73 Moreover, it was suggested that free charge carriers (as opposed to bound charges across the polymer:fullerene interface) are generated from "hot" delocalized states of the charged species.…”

Sub-picosecond delocalization in the excited state of conjugated homopolymers and donor–acceptor copolymers

“…53,74 Finally, the decay of the peak shi in three-pulse photon echo (3-PEPS) experiments allows one to gain insight into the initial excited-state processes in conjugated polymers. [75][76][77][78] In particular, Scholes et al studied MEH-PPV in different solutions and thin lm, observing a characteristic $50 fs peak shi decay component (Fig. 1B).…”