Covalently Bonded Pillared Layered Bromoplumbate with High Thermal Stability: High Capacitance Gain after Photoinduced Electron Transfer

Improving
the stability and photoelectric properties are current aims in the
field of inorganic–organic hybrid lead halides. In this work,
a new covalently bonded pillared layered bromoplumbate, [Pb3Br6(CV)]n, was prepared using
a photoactive zwitterion viologen, N,N′-4,4′-bipyridiniodipropionate (CV), as a ligand. It
has a high thermal stability in air and shows a remarkable increase
of capacitance after photoinduced electron transfer (PIET). The observed
dielectric switch ratio of ∼689% at 3 kHz exceeded all reported
values at room temperature for switchable dielectric materials. The
capacitance gain was derived from the redistribution of electrons
after PIET from the lead-halide layer to organic π-aggregates,
so that the activation energy of hopping polarizability was significantly
reduced.