Optical, electrical, and structural properties of polyethylene oxide/fullerene nanocomposite films

Polyethylene oxide (PEO)/fullerene (C60) nanocomposite films were synthesized through a solution mixing and casting method. The influence of increasing C60 concentration on thermal stability is evident in thermogravimetric analysis (TGA) profiles. TGA is employed to assess the thermal stability of polyethylene oxide (PEO) films, revealing a gradual weight loss below 200°C and pronounced degradation between 200°C and 500°C. PEO films doped with C60 improve their stability, with the 8 wt% C60 film retaining 40 wt% of its initial weight at 425°C—four times greater than the 1 wt% C60 film. XRD patterns exhibit a progressive reduction in crystallinity, decreasing from 52% to 38% with higher C60 content. Furthermore, C60 introduction leads to a reduced transmittance in the visible region, a redshift in the band edge, indicative of decreasing bandgap energy from 3.95 eV to 3.59 eV. Overlapping absorption bands in the extinction coefficient spectra (490 nm–620 nm) corresponded to π-π* and n-π* transition bands of C60. The electrical conductivity of PEO/C60 nanocomposite films demonstrate a substantial increase directly proportional to C60 concentration, reaching approximately 200-fold the conductivity of undoped PEO (2.28 × 10−6) at 8 wt% (1.11 × 10−4 S cm−1).