Optical limiting properties of single-walled carbon nanotube dispersions in amide solvents

Abstract

Single-walled carbon nanotube (SWNT) dispersions were prepared in N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA), respectively. The nonlinear optical properties of SWNT dispersions were studied by using the Z-scan method. The nonlinear extinction coefficients increase significantly with increasing SWNT concentration. In the three dispersions, the DMF dispersions show the strongest nonlinear extinction effect. In conjunction with this, the optical limiting performance is also superior for the DMF dispersions. Compared with DMF and DMA, NMP has a much better debundling effect for SWNTs, however the optical limiting properties of the NMP dispersions is inferior. The static light scattering experiment revealed that the DMF dispersions have the largest average bundle size. The principal mechanism of the optical limiting effect of the SWNT dispersions is due to the solvent and/or carbon vapour bubble-induced nonlinear scattering. The present results indicate that the average bundle size of SWNTs in combination with the thermodynamical properties of the solvent, dominate the nonlinear extinction and optical limiting properties of SWNT dispersions.