The temperature effect
on electronic transport mechanisms
in graphene
nanoplatelet (GNP) doped polydimethylsiloxane (PDMS) for temperature
sensing applications has been investigated under electrical impedance
spectroscopy (EIS) analysis. AC measurements showed a very prevalent
frequency-dependent behavior in low filled nanocomposites due to the
lower charge density. In fact, 4 wt % GNP samples showed a nonideal
capacitive behavior due to scattering effects. Therefore, the standard
RC-LRC circuit varies with the substitution of capacitive elements
by CPEs, where a CPE is a constant phase element which denotes energy
dissipation. In this regard, the temperature promotes a prevalence
of scattering effects, with an increase of resistance and inductance
and a decrease of capacitance values in both RC (intrinsic and contact
mechanisms) and LRC (tunneling mechanisms) elements and, even, a change
from ideal to nonideal capacitive behavior as in the case of 6 wt
% GNP samples. In this way, a deeper understanding of electronic mechanisms
depending on GNP content and temperature is achieved in a very intuitive
way. Finally, a proof-of-concept carried out as temperature sensors
showed a huge sensitivity (from 0.05 to 11.7 °C–1) in comparison to most of the consulted studies (below 0.01 °C–1), proving, thus, excellent capabilities never seen
before for this type of application.