Enhanced performance nanostructured thermoelectric converter for self-powering health sensors

Abstract

Abstract Grain boundaries (Gbs) in polycrystals control the boundary-scattering in the intergranular transport of phonons and electrons, therefore Gbs represent a key design factor for enhancing the thermoelectric properties in polycrystals. Here, extended energy barriers have been created via grain coating by the segregation of 10 nm average thick graphene nanoplatelets (GNps) at the Gbs of N-type and P-type Bi2Te3 thermoelectric polycrytals. By realizing a proof-of concept device, a ZT~1.5 at room temperature has been achieved in comparison to the reference one with ZT~0.9, which represents an increment of around 35% on the maximun output power of the device.The improvement on ZT is mainly related to the enhancement of the thermoelectric power S2σ, as well as the impoverishment of the thermal conductivity k of the materials. Hence, energy barrier extension at Gbs may be an appropriate strategy to filter away low-energy carriers via energy filtering, and thereby to increase ZT. Besides, the thermoelectric converter is able to efficiently harvest heat from temperature gradients as low as 10 °C coming from the human body. Consequently, based on the results, the present research shed a light for the development of self-powering health sensors devices from human body heat which would eliminate the need for batteries, as well as to ensure their long-term powering.