Highly Tunable Molecularly Doped Flexible Poly(dimethylsiloxane) Foam Piezoelectric Energy Harvesters

Despite
considerable research interest in developing piezoelectric materials,
little work has focused on the fundamental design of these materials
from the ground up. Herein, we present a general, versatile method
for producing tunable, flexible piezoelectric energy harvesters (PEHs)
with excellent piezoelectric response. Using a poly­(dimethylsiloxane)
(PDMS) foam derived from a sugar template, we separate the electrical
and mechanical properties of the PEH, thereby allowing us to optimize
them separately. The electrical properties were tuned by varying the
poling field, the polar dopant, and the dopant concentration. The
mechanical properties were tuned by varying foam preparation and thus
the compressive modulus. Through the careful tuning of these properties,
we are able to achieve a maximum piezoelectric response of 153 pC/N,
which is considerably higher than that of most other reported flexible
PEHs. Combined with our previous work, we demonstrate that doping
polymer foams with polar dopants is a highly general strategy and
has the potential to lead to materials with considerably higher piezoelectric
responses.