Carbon Nanotube Electronics and Optical Properties

Carbon nanotubes (CNTs) are cylindrical allotropes of carbon distinguished by exceptional mechanical strength, high carrier mobility and tunable electronic structure. In electronics, semiconducting CNTs serve as the active channels in field-effect transistors, offering subthreshold swings and on-state currents that rival or exceed those of silicon devices at nanoscale dimensions. Their one-dimensional geometry minimises scattering and supports high-frequency operation, making them prime candidates for radio-frequency and flexible integrated circuits. Optically, single-walled carbon nanotubes (SWCNTs) exhibit narrow, chirality-specific absorption and emission in the near-infrared region, underpinned by tightly bound excitons. Covalent and non-covalent functionalisation strategies preserve π-conjugation while enabling tailored photoluminescence and sensing capabilities. Progress in sorting techniques has yielded high-purity chirality ensembles, facilitating reproducible device performance. Across both domains, advances in assembly, integration and exciton engineering are converging to unlock applications in wearable electronics, bioimaging and quantum photonics, establishing CNTs as a versatile platform for next-generation technologies.

Research from Nature Portfolio

Recent studies have systematically correlated the chiral indices of SWCNTs with their charge transport characteristics by fabricating thin-film transistors from films of single-chirality nanotubes. These investigations reveal that even nanotubes of equal diameter can differ by an order of magnitude in carrier mobility and on-state current, driven by variations in band structure, contact resistance and intertube junctions. Such insights provide a design map for selecting optimal chiralities in high-performance transistors. Complementary work has demonstrated industrial-scale chromatographic separation of single-chirality SWCNTs using surfactant-mediated affinity gels, yielding milligram quantities of pure (n,m) species. This capability underpins scalable production of materials for both electronic and bio-optical applications. Additionally, flexible digital and analogue circuits built from ultrahigh-purity semiconducting CNTs have achieved low-voltage operation and high integration density. By employing polymer-sorting, uniform deposition and pseudo-complementary circuit design, ring oscillators and shift registers on plastic substrates now function at gate delays below 50 ns, demonstrating the feasibility of large-area, solution-processed carbon nanotube electronics.

Carbon Nanotube Electronics and Optical Properties publication trend

The graph below shows the total number of articles in carbon nanotube electronics and optical properties across all publications each year (not limited to Nature Index journals).

Technical terms

Chirality: The (n,m) indices defining the wrapping vector of a CNT, determining its electronic and optical properties.

Field-Effect Transistor (FET): A three-terminal device where the conductance of a semiconducting channel is modulated by an electric field.

Carrier Mobility: A measure of how quickly charge carriers (electrons or holes) can move through a semiconductor under an applied electric field.

Exciton: A bound electron-hole pair in a semiconductor that governs optical absorption and emission processes.

Photoluminescence: Light emission resulting from radiative recombination of photoexcited carriers or excitons.

Spin-On-Glass (SOG): A sol–gel-derived silica dielectric applied in thin films by spin coating, used for interlayer insulation.

Pseudo-CMOS Design: A circuit architecture that emulates CMOS logic using unipolar transistors by combining complementary device behaviours.

Fluorescence Lifetime Imaging Microscopy (FLIM): A technique that maps spatial variations in fluorescence decay times, providing contrast independent of intensity.

References

1. Chirality-dependent electrical transport properties of carbon nanotubes obtained by experimental measurement. Nature Communications (2023).
2. Industrial-scale separation of high-purity single-chirality single-wall carbon nanotubes for biological imaging. Nature Communications (2016).
3. Low-voltage high-performance flexible digital and analog circuits based on ultrahigh-purity semiconducting carbon nanotubes. Nature Communications (2019).
4. Monolithic three‐dimensional integration of aligned carbon nanotube transistors for high‐performance integrated circuits. InfoMat (2023).
5. Carbon nanotube integrated circuit technology: purification, assembly and integration. International Journal of Extreme Manufacturing (2024).
6. Near‐Infrared Fluorescence Lifetime Imaging of Biomolecules with Carbon Nanotubes**. Angewandte Chemie International Edition (2023).
7. Preserving π-conjugation in covalently functionalized carbon nanotubes for optoelectronic applications. Nature Communications (2017).