Can we use the ghostly neutrinos as messenger for the signals to transfer from one point to other. Is it the best source of communication where the light cannot go?
An oft-quoted figure is that takes ~ 1/3 light-year of lead to stop half the flux of a neutrino source.
Which, if you're willing to generate them at a prodigious rate, is not a problem.
If your receiver is, say, Super Kamiokande, you might get a dozen counts per day from the Sun.
So if you had a neutrino source as luminous as the Sun, and could modulate it at will (!) you could manage a bandwidth of about 1 micro baud over a 1AU distance.