  The signatures of polycyclic aromatic hydrocarbons (PAHs) have been observed
in protoplanetary discs, and their emission features obtained from spectral
energy distributions (SED) have been used in the literature to characterise
their size and determine their abundance. Two simple disc models (uniform PAH
distribution against a PAH gap in the inner disc) are compared to investigate
the difference of their SED and obtainable information. We used the radiative
transfer code RADMC-3D to model the SED of two protoplanetary discs orbiting a
typical Herbig star, one of which features a depletion of PAHs in the inner
disc. We further created artificial images of the discs at face-on view to
extract radial profiles of the PAH emission in the infrared. We find that the
extracted PAH features from an SED provide limited information about the PAHs
in protoplanetary disc environments, except for the ionisation state. The
distribution of PAHs in a protoplanetary disc influences the total observed PAH
luminosity in a non-linear fashion and alters the relative strength between the
3.3\,$\mu$m and 11.3\,$\mu$m features. Furthermore, we produced radial profiles
at the 3\,$\mu$m, 6\,$\mu$m and, 11\,$\mu$m PAH emission features and find that
they follow a double power-law profile where the slope reflects the radiative
environment (single photon regime vs. multi-photon regime) in which the PAHs
lie. Using spatially resolved techniques such as IFU or imaging in the era of
the James Webb Space Telescope, we find that multi-wavelength radial emission
profiles will not only provide information on the spatial distribution of the
PAHs, but may also provide information on their size and underlying UV
environment, which is crucial for photo-evaporative disc wind models.
