Semiconductor single-walled carbon nanotubes (SWNT) are known to have useful properties such as high electrical conductivity and strength.   They are however limited in their use in applications that rely on their fluorescence properties such as labeling and in display technology. This limitation is due to low fluorescence emission (less  that 1% quantum yield) that result from fast non-radiative exciton relaxation caused by the presents of surface defects.We present here, single molecule fluorescence studies performed at room temperature on DNA-wrapped SWNT in the presence of reducing agents like DTT, BME and Trolox. In addition to  strong photo-stability (no blinking) for minutes without spectral diffusion, we also observe about a four fold increase in the fluorescence intensity and an order of magnitude increase in quantum yield, when SWCNTs are treated with such reductants. We propose that passivation of surface defect sites and in particular hole-trap states by the reductants render  radiative relaxation pathways as the more efficient route for excited state decay and there by increase the fluorescence emission and quantum yield of the SWCNTs. Our results shed new light on the the effect of reductants on the excited state decay dynamics of SWCNTs.

Effect of reductants on the fluorescence properties of single  walled carbon nanotube

244th National Meeting (2012)

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