Figure 1.
Cold-fractured cross sections of Sample 4 (A), Sample 5 (B), Sample 6 (C) (see
Table 1). With increasing gold vol% and decreasing PEDOT∶PSS vol%, more CNTs were pulled out from the surface. The arrows indicate CNTs and gold nanoparticles. All scale bars indicate 1 µm.
Table 1.
List of the composites with all contents and their vol%.
Figure 2.
Electrical conductivity (A) and thermopower (B) of Sample 1∼6 (see Table 1).
The vol% of HSWCNT and polymer (Vinnapas 401 or BP600) was 60 and 10. The ratio of PEDOT∶PSS to gold was 2∶1, 1∶1, or 1∶2.
Figure 3.
(A) The energy barrier constant, T1 in Eq. (2) as a function of CNT vol% (red filled circles).
(B) The normalized factor (σo,Au/σo,NoAu) that indicates the effect of gold doping for CNT networks and electrical conductivity of gold-incorporated CNT networks (σo,Au) for Sample 1∼6. T1 was found from the electrical conductivities (σc) of similar composites (blue hollow squares) containing 60-wt% HSWCNT, 30-wt% PEDOT∶PSS, 10-wt% PVAc from our previous work [14]. For σo,Au and σo,NoAu, tube-tube junction resistances in CNT networks were not considered.
Figure 4.
Cold-fractured cross sections of Sample 7 (A), Sample 8 (B), Sample 9 (C), and Sample 10 (D) (see Table 1).
Long CSWCNTs were pulled out from the polymer whereas short MWCNTs were aggregated together in (A) and (B). Relatively rough surfaces with aggregated gold particles were observed in (C) and (D). All scale bars indicate 1 µm.
Figure 5.
Electrical conductivity (A) and thermopower (B) of Sample 7∼10 along with those of Sample 5 and a sample in Ref. 14 for comparison.
The sample in Ref. 14 contains 60-wt% (54.6 vol%) HSWCNT, 30-wt% (35.5 vol%) PEDOT∶PSS, and 10-wt% (9.9 vol%) PVAc. HSWCNT show higher conductivities than the MWCNT- and CSWCNT-filled composites, even after gold nanoparticles were incorporated.