Simultaneously Achieving Green p- and n-Type Single-Walled Carbon Nanotube Composites by Natural Amino Acids with High Performance for Thermoelectrics

Abstract

Many drugs, foods, and clothes are derived from natural products; however, little attention has been focused on natural-derived thermoelectric (TE) materials. In this work, several natural amino acids are first introduced to single-walled carbon nanotubes (SWCNTs) and a series of environment-friendly n- and p-type freestanding SWCNT/amino acid films are fabricated as potent TE materials. Among the composites, SWCNT/histidine (His) and SWCNT/lysine (Lys) achieve excellent n-type TE properties, with the highest power factors of 508.5 and 502.0 μW m–1 K–2 at room temperature, respectively. SWCNT/aspartic acid (Asp) displays p-type behaviors, with the highest power factor of 221.6 μW m–1 K–2 at room temperature. Moreover, a TE device based on SWCNT/Lys and SWCNT/Asp including five p–n junctions is fabricated. The high open-circuit voltage (42.3 mV) and output power (4.3 μW) are obtained at ΔT = 87 K. Given the excellent TE performance, green composites based on natural-derived materials can be the promising candidates for TE devices.

Developing Air-Stable n-Type SWCNT-Based Composites with High Thermoelectric and Robust Mechanical Properties for Wearable Electronics

“…This might be attributed to the actual temperature difference at both ends of the device being smaller than the given value . However, as seen from Table S3, the output power density of the device in our work is comparable to or even higher than that of n-type SWCNT-based thermoelectric materials, which is suitable for powering wearable electronics. ,,,− ,,, …”

Flexible Thermopiles Based on Hydrogels with Carriers Moving in Opposite Directions

“…In addition, the reported thermoelectric power outputs are normalized and designated as “specific power” by dividing them by the mass of the material and the square of the temperature difference . In comparison to the performance of the thermopiles in e-textiles reported previously, ,,− the Seebeck coefficient and specific power in this work are significantly improved.…”

“…To improve the thermoelectric performance, p-type (carriers with positive charge) and n-type (carriers with negative charge) thermoelectric materials have been connected in series to form thermopiles, which can superimpose the performance of multiple p–n pairs. , Currently, the reported thermopiles are mostly composed of materials with differently charged carriers, and their thermal motion directions are always considered to be from hot to cold. , However, compared to p-type polymers, n-type polymers are less abundant and usually exhibit poor thermoelectric properties. This is because their electron affinity values are too low to stabilize the n-type dopants, and the thermoelectric properties of n-type polymers can be severely degraded by atmospheric oxygen .…”

All-Solution-Processed Polythiophene/Carbon Nanotube Nanocomposites Integrated on Biocompatible Silk Fibroin Substrates for Wearable Thermoelectric Generators

“…Carbon allotrope-based thermoelectric materials, particularly carbon nanotubes (CNTs), are generally characterized by good electrical properties, high thermal stability, and high thermal conductivity. − Therefore, tunable amounts of carbon-based nanofillers are usually added to conducting polymer nanocomposites to improve their electrical charge transport and thermoelectrical properties. − The interfaces between nanofillers and conjugated polymers in the nanocomposites can form a specific charge-carrier pathway, resulting in an energy-filtering effect that enhances the Seebeck coefficient ( S ) without compromising the electrical conductivity (σ). − Although CNTs have excellent σ that can compensate for the low σ of polymer matrices, the adequate dispersion of CNTs within nanocomposites is still an essential issue for conducting solution processing and achieving large-area and high-throughput thermoelectric devices. This difficulty in dispersing CNTs is overcome by introducing the surfactant or conjugated polymers through intermolecular interactions between CNTs and polymers. − However, using vacuum filtration for bulk or film thermoelectric nanocomposites is a poor strategy since free-standing thermoelectric nanocomposites need to be cut and interconnected by conducting electrodes for the module to be used .…”