  We identified different nano-carbon species such as graphene nanoplatelets,
graphite flakes and carbon nanotubes dispersed in N-methyl-2-pyrrolidone using
a novel sensor structure based on a "deep" silicon barrier working as a
photoelectrical transducer. Each nano-carbon particle has specific signature in
both 2D photocurrent distribution and photocurrent dependences on bias changing
surface band-bending. Additionally, all nano-carbon particles have
characteristic features in the time-dependent evolution of photocurrent. The
obtained results can be explained by the influence of nano-carbon molecules'
local electric field on the recombination parameters of defect centers on the
silicon surface.
