Two conductive carbon materials, one with a beaded-like structure (carbon black, ECP) and another with tube-like structure (functionalized multi-walled carbon nanotubes, FMWCNTs), were added into a poly(amide-imide) (PAI) matrix. Combining the advantages of ECP (good compatibility) and FMWCNT (high conductivity), the conductivity was improved from 3.7 S m−1 for PAI/FMWCNT polymer composites to 100 S m−1 for PAI/FMWCNT/ECP ternary conductive polymer composites, much higher than that of the sum of PAI/ECP and PAI/FMWCNT. The tensile strength increased from 40 to 70 MPa. The improved conductive and mechanical properties were mainly due to much more intensive conductive network produced in the PAI/FMWCNT/ECP ternary composites, which is useful for electron flow and stress spread. The number of hydrogen bond was increased by adding ECP into PAI/FMWCNT binary composites, and played an important role in forming the unique morphology as evident by Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD) measurements. These conductive composites have potential for flexible electronic applications.

A non-fullerene molecule named Y6 was incorporated into a binary blend of PBDB-T and IT-M to further enhance photon harvesting in the near-infrared (near-IR) region. Compared with PBDB-T/IT-M binary blend devices, PBDB-T/IT-M/Y6 ternary blend devices exhibited an improved short-circuit current density (JSC) from 15.34 to 19.09 mA cm−2. As a result, the power conversion efficiency (PCE) increased from 10.65% to 12.50%. With an increasing weight ratio of Y6, the external quantum efficiency (EQE) was enhanced at around 825 nm, which is ascribed to the absorption of Y6. At the same time, EQE was also enhanced at around 600–700 nm, which is ascribed to the absorption of IT-M, although the optical absorption intensity of IT-M decreased with increasing weight ratio of Y6. This is because of the efficient energy transfer from IT-M to Y6, which can collect the IT-M exciton lost in the PBDB-T/IT-M binary blend. Interestingly, the EQE spectra of PBDB-T/IT-M/Y6 ternary blend devices were not only increased but also red-shifted in the near-IR region with increasing weight ratio of Y6. This finding suggests that the absorption spectrum of Y6 is dependent on the weight ratio of Y6, which is probably due to different aggregation states depending on the weight ratio. This aggregate property of Y6 was also studied in terms of surface energy.

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A series of novel ternary conductive composites have been prepared by incorporating functionalized multiwalled carbon nanotubes (FMWCNTs) into the binary composites of poly(amide-imide) (PAI) and poly( o-methoxyaniline) (POMA) to further improve the conductivity of PAI composites. With increasing the weight ratio of FMWCNTs, the conductivity of PAI/POMA/FMWCNTs ternary composites has been significantly enhanced from 10−3 S m−1 to 90 S m−1, much higher than that of the sum of PAI/POMA and PAI/FMWCNTs binary composites. The enhanced conductivity is mainly ascribed from a much more intensive conductive network formed in the PAI/POMA/FMWCNTs ternary composites. It is found that the N–H bending of amide group in the Fourier transform infrared spectrometry spectra is observed at 3298 cm−1 for PAI, 3296 cm−1 for PAI/POMA binary composites, and further blue shifted to 3292 cm−1 for PAI/POMA/FMWCNTs ternary composites. Moreover, the glass transition temperature has been increased from 82.5°C to 117.7°C. These results suggested that the hydrogen bonding interaction has been strengthened among PAI, POMA, and FMWCNTs, which is useful for dispersion of condcutive fillers into the polymer matrix.