Figure 5: Polaron pair generation and recombination dynamics.
From: Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics
Time-resolved polaron pair generation after photoexcitation for the co-polymers: (a) PCPDT-BDT, (b) PCPDT-BT, (c) PCPDT-2TTP, (d) PCPDT-2TBT and (e) the homopolymer P3HT. The polaron pair generation yields are η=(24±1)%, (20±1)%, (23±2)%, (15±1.5)% and (8±2)% for PCPDT-BDT, PCPDT-BT, PCPDT-2TTP, PCPDT-2TBT and P3HT, respectively. The respective pump and probe photon energies are indicated in Fig. 2. The pump photon energy for P3HT is 3.1 eV. The insets illustrate the variations in the polymer repeat units in terms of donor acceptor centre of mass distance (arrows) and acceptor strength (colour coded yellow to red). The inset in b show the pump-probe instrument response function (IRF) for 1.55 eV (800 nm) pump and 0.41 eV (3,000 nm) probe. Solid lines are fit to the data points which are shown as squares.
