Session 6-2

Abstract

Isolated semiconducting single-walled carbon nanotubes (SWCNTs) have been shown to exhibit narrowband near-infrared thermal radiation at high temperatures [1-3]. This phenomenon originates from the thermal exciton effect, where thermally generated excitons—quasiparticles composed of mutually bound electrons and holes—undergo radiative recombination. The strong Coulomb interaction in SWCNTs results in exciton binding energies of more than a few hundred meV, corresponding to thermal energy at several thousand kelvin. This exceptional stability allows excitons to persist and be generated thermally even at high temperatures, making SWCNTs ideal platforms for fundamental thermal science of excitons, as well as for applications that require high intensity near-infrared emitters such as thermophotovoltaics.

For the practical application of the thermal exciton effect on a macroscale, it is essential to demonstrate that this unique excitonic property can be harnessed in macroscopic assemblies of SWCNTs. As a critical step toward this goal, we have systematically investigated the fundamental optical properties [4,5] and thermal stabilities [6] of single-chirality SWCNT thin films at high temperatures. Building upon these foundational works, I will report our latest findings on the photophysical properties of isolated and aggregated SWCNTs at high temperatures, including exciton luminescence to thermal radiation crossover [3], spectral emissivity spectra at high temperatures [7], and our recent observations of robust exciton binding energy in aggregated SWCNTs [8].