Construction
of an inorganic/organic superlattice-based film has
been proven effective in enhancing thermoelectric (TE) performance
as well as flexibility by a variety of mechanisms, typically for two-dimensional
(2D) TiS2-based flexible TEs. MXenes, typically, Ti3C2T
x
, are a type of
2D material widely investigated in fields of flexible batteries and
electromagnetic shielding, among others. However, they have rarely
been reported in flexible TEs. One of the key factors is that the
surface termination groups (−T) on an MXene could trap electrons,
restricting the electronic transport. Herein, −T groups were
tailored and substituted by organic ions (−HA) by facile preannealing,
exfoliation, and reassembly. The intercalation of −HA introduced
Ti–N bonding, forming a flexible MXene/organic superlattice
film. The electrical conductivity of the superlattice film was increased
by 5 times to 1.6 × 105 S m–1 due
to defect reduction as well as the electron injection effect. While
the Seebeck coefficient was maintained, the power factor was increased
from 4 to 18 μW m–1 K–2.
The TE module based on the superlattice film revealed an output power
of 7.6 nW at a temperature gap of 50 K. This work opens up an avenue
of fabricating flexible MXene-based TE films by tailoring the surface
termination group and constructing inorganic/organic superlattice
structures.