  Networks of nanowires and nanosheets are important for many applications in
printed electronics. However, the network conductivity and mobility are usually
limited by the inter-particle junction resistance, a property that is
challenging to minimise because it is difficult to measure. Here, we develop a
simple model for conduction in networks of 1D or 2D nanomaterials, which allows
us to extract junction and nanoparticle resistances from
particle-size-dependent D.C. resistivity data of conducting and semiconducting
materials. We find junction resistances in porous networks to scale with
nanoparticle resistivity and vary from 5 Ohm for silver nanosheets to 25 GOhm
for WS2 nanosheets. Moreover, our model allows junction and nanoparticle
resistances to be extracted from A.C. impedance spectra of semiconducting
networks. Impedance data links the high mobility (~7 cm2/Vs) of aligned
networks of electrochemically exfoliated MoS2 nanosheets to low junction
resistances of ~670 kOhm. Temperature-dependent impedance measurements allow us
to quantitatively differentiate intra-nanosheet phonon-limited band-like
transport from inter-nanosheet hopping for the first time.
