Semiconducting polymer contributes favorably to the Seebeck coefficient in multi-component, high-performance n-type thermoelectric nanocomposites

Abstract

n-Type semiconducting polymers bearing high Seebeck coefficients (S) have been seldom employed in organic–inorganic thermoelectric nanocomposites (TENCs). Herein we illustrate how to exploit an n-type semiconducting polymer to fabricate TENCs comprising N2200 and metallic Co NWs, in which N2200 contributes significantly to the S of the TENCs. The TENCs exhibit a highest power factor (PF) of 288 μW m⁻¹ K⁻² at 80 wt% Co NWs. At a greater Co NW content, the organic/inorganic inter-connectivity deteriorates, owing to the rigid molecular chains of N2200, retarding the increase of electrical conductivity (σ) and also undermining the mechanical flexibility. Flexible n-type doped SWCNTs were therefore added to introduce additional conductive paths. At an optimal amount of SWCNTs (2 wt%), the σ increases to 1860 S cm⁻¹, whereas S remains at approximately −45 μV K⁻¹ and the bendability is improved. The maximal PF and zT values of the resulting ternary TENC reach 483 μW m⁻¹ K⁻² and 0.18 at 380 K, respectively. By pairing with p-type PEDOT:PSS/SWCNT thin films, the 6-legged flexible TEG yields maximum output voltage and power of 9.80 mV and 3.72 μW, respectively, when ΔT = 50 K. This work manifests a new avenue to both highly efficient and bendable thermoelectric materials through the judicious choice of multiple blend components.