Tuning exciton-polariton populations in thin films of single-walled carbon nanotubes

Thin films of semiconducting single-walled carbon nanotubes (SWCNTs) are ideal for strong light-matter coupling. We demonstrate optically and electrically pumped near-infrared exciton-polaritons at room temperature and the possibility to tune between weak, strong and ultrastrong coupling in field-effect transistors [Nat. Mater. 2017, 16, 911] and electrochromic devices [ACS Photonics 2018, 5, 2074]. While these polaritons are observed in simple metal-clad microcavities, coherent coupling of carbon nanotube excitons with hybrid plasmon-photonic modes results in plasmon-exciton polaritons (‘plexcitons’) [Nano Lett. 2018, 18, 4927]. Furthermore, covalent functionalization of SWCNTs creates luminescent defects with red-shifted emission. Without changing the polariton branch structure, radiative pumping through these emissive defects leads to an up to 10-fold increase of the polariton population in microcavities with detunings for large photon fractions [ACS Photonics 2021, 8, 182].