Photoresponsive Thermoelectric Materials Derived from Fullerene-C60 PEDOT Hybrid Polymers

Abstract

A series of fullerene-C60-PEDOT hybrid polymers HP1–7 with different contents of C60 were successfully prepared and characterized in terms of UV–vis absorption spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Poly­(3,4-ethylenedioxythiophene) (PEDOT) chains were grafted onto the surface of C60, where C60 was covalently dispersed into the whole hybrid polymer network. The thermoelectric (TE) properties of hybrid polymer films were investigated in the dark condition and under visible light irradiation. In the dark condition, the HP1 (0.00 wt % C60) films showed an electrical conductivity (σ) of 240 ± 5 S cm–1 and a Seebeck coefficient (S) of 10 ± 0.6 μV K–1. By increasing the C60 content in hybrid polymers, the σ gradually decreased to 70 ± 10 S cm–1 (HP7, 5.00 wt % C60). In contrast, the S rapidly increased to 19 ± 0.5 μV K–1 (HP4, 1.00 wt % C60) and then reached 22 ± 1.0 μV K–1 for HP7. A maximum power factor (PF) of 5.8 ± 0.2 μW m–1 K–2 was achieved for HP3 films with 0.50 wt % C60. Under light irradiation, the S of HP2–4 were decreased from 13 ± 0.8, 17 ± 0.9, and 19 ± 0.5 to 9 ± 0.4, 8 ± 0.6, and 12 ± 0.4 μV K–1, respectively, leading to decreased PFs of 1.9 ± 0.2, 1.5 ± 0.1, and 2.4 ± 0.2 μW m–1 K–2, respectively. HP3 exhibited the highest light-inhibited efficiency of the TE property with its PF of approximately one-fourth of that obtained under visible light irradiation, revealing that the TE performance of these fullerene-C60-PEDOT hybrid polymers could be feasibly controlled by the irradiation of the visible light.