  In this work we derive a general expression for the greybody factor of
non-minimally coupled scalar fields in Reissner-Nordstr\"om-de Sitter spacetime
in low frequency approximation. In particular case of zero momentum, greybody
factor tends to zero in low frequency limit as frequency squared goes to zero
for non-vanishing coupling. We also elaborate the significance of the results
by giving formulae of differential energy rate and general absorption cross
section. The greybody factor gives insight into the spectrum of Hawking
radiations.
