Observation of rapid Auger recombination in optically excited semiconducting carbon nanotubes

Time-resolved fluorescence measurements of single-walled carbon nanotubes (SWNTs) reveal rapid electron-hole pair annihilation when multiple electron-hole pairs are present in a nanotube. The process can be understood as Auger recombination with a rate of $\sim 1{\mathrm{ps}}^{-1}$ for just two electron-hole pairs in a 380-nm long SWNT. This efficient nonradiative recombination reflects the strong carrier-carrier interactions in the quasi-one-dimensional SWNTs. In addition to affecting nanotube fluorescence, Auger recombination imposes limitations on the sustained electron-hole density achievable within a SWNT.

Figure 1

(Color) Experimental time-resolved fluorescence decay curves for SWNTs excited at the indicated pump fluences. The gray curves are fits using the model described in the text. The inset shows a log-linear plot of the same data. The equivalence of the trailing part of the decay at all fluences is apparent.

Figure 2

The dependence of the integrated fluorescence emission in the slow (squares) and the fast (triangles) components as a function of the excitation pump fluence. The curves are fits to the model described in the text.