High-Power All-Carbon Fully Printed and Wearable SWCNT-Based Organic Thermoelectric Generator

In this study, we introduce the fabrication process of a highly efficient fully printed all-carbon organic thermoelectric generator (OTEG) free of metallic junctions with outstanding flexibility and exceptional power output, which can be conveniently and rapidly prepared through ink dispensing/printing processes of aqueous and low-cost CNT inks with a mask-assisted specified circuit architecture. The optimal p-type and n-type films produced exhibit ultrahigh power factors (PFs) of 308 and 258 μW/mK², respectively, at ΔΤ = 150 K (T_HOT = 175 °C) and outstanding stability in air without encapsulation, providing the OTEG device the ability to operate at high temperatures up to 200 °C at ambient conditions (1 atm, relative humidity: 50 ± 5% RH). We have successfully designed and fabricated the flexible thermoelectric (TE) modules with superior TE properties of p-type and n-type SWCNT films resulting in exceptionally high performance. The novel design OTEG exhibits outstanding flexibility and stability with attained TE values among the highest ever reported in the field of organic thermoelectrics, that is, open-circuit voltage V_OC = 1.05 V and short-circuit current I_SC = 1.30 mA at ΔT = 150 K (T_HOT = 175 °C) with an internal resistance of R_TEG = 806 Ω, generating a 342 μW power output. It is also worth noting the remarkable PFs of 145 and 127 μW/mK² for the p-type and n-type films, respectively, at room temperature. The fabricated device is highly scalable, providing opportunities for printable large-scale manufacturing/industrial production of highly efficient flexible OTEGs.