Long-Term Improvements to Photoluminescence and Dispersion Stability by Flowing SDS-SWNT Suspensions through Microfluidic Channels

Abstract

Shearing single-walled carbon nanotubes (SWNTs) coated with sodium dodecyl sulfate in microfluidic channels significantly increases the photoluminescence (PL) intensity and dispersion stability of SWNTs. The PL quantum yield (QY) of SWNTs improves by a factor of 3 for initially bright suspensions; on the other hand, SWNT QYs in a "poor" suspension improve by 2 orders of magnitude. In both cases, the QYs of the sheared suspensions are approximately 1%. The increases in PL intensity persist for months and are most prominent in larger diameter SWNTs. These improvements are attributed to surfactant reorganization rather than disaggregation of SWNTs bundles or shear-induced alignment. The results also highlight potential opportunities to eliminate discrepancies in the PL intensity of different suspensions and further improve the PL of SWNTs by tailoring the surfactant structure around SWNTs.