Improved thermoelectric performance of PEDOT:PSS/Bi2Te3/reduced graphene oxide ternary composite films for energy harvesting applications

Abstract

We report a significant enhancement in the thermoelectric power of PEDOT by fabricating a novel ternary composite film by incorporating Bi₂Te₃ and rGO. A series of five samples of PEDOT:PSS/Bi₂Te₃/rGO ternary composite films were synthesized using a spin coating method and having different weight% (0.0, 0.1, 0.2, 0.3 wt%) of rGO in PEDOT:PSS/0.4 wt% Bi₂Te₃ mixture along with pure PEDOT:PSS sample. The Seebeck coefficient, electrical conductivity, and power factor increased in composite films compared to pure PEDOT:PSS films. Incorporating rGO enhanced charge carrier mobility because of its highly conductive network, whereas Bi₂Te₃ provided higher Seebeck coefficients owing to its inherent thermoelectric properties. PEDOT:PSS offered mechanical flexibility and a conductive matrix, facilitating effective phonon scattering and inherently lower thermal conductivity. The sample (PEDOT:PSS/0.4 wt% Bi₂Te₃/0.1 rGO wt%) demonstrated the highest electrical conductivity of 1522.4 S cm⁻¹, a Seebeck coefficient of (+) 24.7 μV K⁻¹, and a power factor of 93.16 μW m⁻¹ K⁻² at room temperature. These values represent a twelve-fold increase compared to pristine PEDOT films. A flexible, printable thermoelectric generator (TEG) was also demonstrated on polyimide substrate using inks prepared from p-type PEDOT:PSS/Bi₂Te₃/rGO and n-type PVDF/Ni NWs. The paper TEG achieved a maximum power output of 242.1 nW, with an output voltage of 9.84 mV and an output current of 49.21 μA at a temperature difference (ΔT) of 35 K. XRD, Raman spectroscopy SEM, and XPS techniques were used to understand the underlying mechanism. This novel PEDOT:PSS/Bi₂Te₃/rGO ternary composite film significantly outperforms previously reported organic thermoelectric materials. The results indicate that the combined effect of PEDOT:PSS, Bi₂Te₃, and rGO greatly enhances thermoelectric performance, offering a promising and efficient route for the application of PEDOT in advanced thermoelectric conversion processes.