Fig. 5

Morphology effect on iPP-mediated hole transfer. TA traces probed at a 2.05 eV and b 2.52 eV recorded from the blend samples before (as-prepared) and after annealing at 110 and 200 °C, respectively. c TA spectra recorded at a time delay of 30 fs recorded from the blend samples annealed at different temperatures. The spectra are normalized at to the signal probed at 1.75 eV (Fig. 5c) to compare the relative signal amplitudes of iPPs in different blends. The photon energy of the pump beam is 1.75 eV. PiFM images show the morphologies of the blend samples d before (as-prepared) and after annealing at e 110 °C and f 200 °C, respectively. The characteristic FTIR wavelengths corresponding to the polymer donor (1061 cm⁻¹, green) and the polymer acceptor (1712 cm⁻¹, red) are selected for better contrast of the PiFM images. The scale bar is 50 nm in d, e, and f. g The amplitude ratio between the signals probed at 2.52 eV and 1.75 eV probed at the delay of 30 fs and the estimated efficiency of iPP generation (η) are plotted versus annealing temperature. Error bars represent standard deviations in the determination of the iPP generation efficiencies obtained by averaging several experiments