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Robust Exciton Binding Energy in Aggregated Structure-Sorted Carbon Nanotubes Revealed by Two-Photon Excitation
Zhirui Liu1, Taishi Nishihara2,3, Vasili Perebeinos4
1Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan.
ACS Nano
|November 30, 2025
Summary
Exciton binding energy in aggregated single-walled carbon nanotubes (SWCNTs) was quantified. These findings highlight the potential of SWCNT assemblies as optofunctional materials at various temperatures.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Single-walled carbon nanotubes (SWCNTs) display sharp excitonic resonances in their optical spectra, even in macroscale assemblies.
- This property suggests potential applications for SWCNT assemblies as excitonic optofunctional materials.
- The exciton binding energy in high-purity, structure-sorted SWCNT membranes is not yet fully understood, despite its importance for excitonic resonance.
Purpose of the Study:
- To investigate and quantify the modifications to exciton binding energy in high-purity, structure-sorted semiconducting SWCNTs upon aggregation.
- To determine the exciton binding energy in aggregated SWCNT membranes and compare it to isolated SWCNTs.
Main Methods:
- Preparation of SWCNT membranes with high single chiral structure purity.
- Utilized one- and two-photon spectroscopies to observe changes in the exciton Rydberg series.
- Performed theoretical calculations to deduce exciton binding energy.
- Measured mid-infrared optical properties to determine the infrared dielectric constant.
Main Results:
- Observed shrinkage in the energy spacing of the exciton Rydberg series in aggregated SWCNTs.
- Deduced an exciton binding energy of approximately 0.26 eV for the aggregated SWCNT membrane.
- This value represents about 80% of the exciton binding energy found in isolated SWCNTs.
- Experimental results were consistent with independently determined infrared dielectric constants.
Conclusions:
- The exciton binding energy in aggregated SWCNT membranes is significantly retained, approximately 80% of that in isolated SWCNTs.
- These findings demonstrate the viability of utilizing exciton resonances in SWCNT aggregations for optofunctional applications across a range of temperatures.
- The study provides crucial insights into the behavior of excitons in SWCNT assemblies, paving the way for advanced material design.
