[15a-A403-1~11] 17.1 Carbon nanotubes & other nanocarbon materials

▲ [15a-A403-7] Radiative quantum efficiency of bright excitons in carbon nanotubes

〇Hidenori Machiya^1,2, Akihiro Ishii¹, Yuichiro K. Kato¹ (1.RIKEN, 2.Univ. of Tokyo)

Keywords:carbon nanotube, Purcell effect, photoluminescence

Carbon nanotubes have potential applications as telecom-band single-photon emitters at room temperature, and coupling to microcavities can further improve the performance through the Purcell effect that accelerates the radiative decay into the cavity mode [1,2,3]. One of the key physical quantity in this process is the radiative quantum efficiency, or the fraction of photons emitted from excitons. The accelerated decay can be directly observed in the time domain if the radiative quantum efficiency is high enough, and this behavior allows for determination of the radiative quantum efficiency without the need to deconvolve the exciton generation efficiency from the photoluminescence (PL) quantum yield.
Here we experimentally determine the radiative quantum efficiency of bright excitons in carbon nanotubes [4]. Utilizing ultralow-mode-volume air-mode cavities, the radiative decay rates are enhanced through the Purcell effect. Time-resolved PL measurements are used to probe the overall decay process including the non-radiative paths, and we observe PL decay rates accelerated by as much as 3 times compared to typical uncoupled air-suspended nanotubes [5]. We further analyze the PL spectra by Monte-Carlo simulation of the cavity-enhanced dynamics of the exciton, extracting the Purcell factors in these devices. Combining the results from time-domain and spectral-domain measurements, we find that the radiative quantum efficiency of the bright exciton is unexpectedly high.
[1] R. Miura et al., Nat. Commun. 5, 5580 (2014).
[2] A. Jeantet et al., Phys. Rev. Lett. 116, 247402 (2016).
[3] A. Ishii et al., Nano Lett. 18, 3873 (2018).
[4] H. Machiya et al., in preparation.
[5] A. Ishii et al., Phys. Rev. X. 9, 041048 (2019).