The X-ray diffraction pattern of annealed and pristine C60 films in the range (a) 2θ = 6°–25°, (b) 2θ = 8°–13°; the miller indices are denoted on the Bragg scattering bands. The inset in (b) shows the chemical structure of C60. TEM images of annealed (c) and pristine (d) C60 films; the grey grains are C60 microcrystallites. The scale bar is 50 nm. Also shown are the grain size distributions extracted from the TEM images for the annealed (e) and pristine (f) C60 films.
Photomodulation spectra of annealed (a) and pristine (b) C60 films atT = 50 K and IL = 0.2 W/cm2 for B = 0 (black lines) and B = 180 mT (red lines). The blue negative lines are the difference spectra ΔPA = PA (B = 180 mT)-PA(0).
(a) MPA(B) response of an annealed C60 film at various pump excitation intensities, measured at photon energy E = 1.8 eV and T = 50 K. (b) The spectra ΔPA(B 1,B 2,E) for B 1 = 0, B 2 = 20 mT (black line, lower curves), and B 1 = 20 mT, B 2 = 180 mT (blue line, upper curves) for IL = 1.5 W/cm2. The smooth green and red lines through the data are to guide the eye and show the TE- and polaron-related MPA bands, respectively.
MC(B) response of an annealed C60 diode for various bias voltages measured at T = 10 K. (a) high resolution for |B| < 0.2 T; (b) low resolution for |B| < 1 T. (c) MC(B) response of devices based on 13C-rich C60 (black line) compared with that of devices based on regular C60 (red line) for |B| < 40 mT.
(a) PL spectrum and (b) MPL(B) response of annealed C60 film at T = 50 K.
Model fitting for MPA(B) of C60. (a) Low field, |B| < 40 mT. The blue line is calculated based on the TE mechanism (see text); the black points are measured MPA(B) taken from Fig. 3(a) . (b) Intermediate field, |B| < 0.2 T. Blue line: calculated using the “Δg mechanism” (see text); black line: measured MPA(B) response taken from Fig. 3(a) .
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