n-Type thermoelectric elastomers.

Intrinsically elastic thermoelectric generators with superior conformal coverage and shape adaptability are highly desirable for developing self-powered wearable electronics, soft bioelectronics and personal temperature regulators. Until now, all reported high-performance thermoelectric materials have realized only flexibility, rather than elasticity. Here we present one of the first n-type thermoelectric elastomers by integrating uniform bulk nanophase separation, thermally activated crosslinking and targeted doping into a single material. The thermoelectric elastomers could exhibit exceptional rubber-like recovery of up to 150% strains and high figure of merit values rivalling flexible inorganic materials even under mechanical deformations. Conventional wisdom suggests that incorporating insulating polymers should dilute the active component in organic thermoelectrics, resulting in lower performance. However, we demonstrate that carefully selected elastomers and dopants can promote the formation of uniformly distributed, elastomer-wrapped and heavily n-doped semiconducting polymer nanofibrils, leading to improved electrical conductivity and decreased thermal conductivity. These thermoelectric elastomers have the potential to make elastic thermoelectric generators in wearable applications much more conformable and efficient.