Fully direct written organic micro-thermoelectric generators embedded in a plastic foil

Organic materials have attracted great interest for thermoelectric applications due to their tuneable electronic properties, solution processability and earth-abundance, potentially enabling high-throughput realization of low-cost devices for low-power energy harvesting applications. So far, organic thermoelectricity has primarily focused on materials development, with less attention given to integrated generators. Yet, future applications will require the combination of efficient generators architectures and scalable manufacturing techniques to leverage the advantages of such promising materials. Here we report the realization of a monolithic organic micro-thermoelectric generator (μ-OTEG), using only direct writing methods, embedding the thermoelectric legs within a plastic substrate through a combination of direct laser writing and inkjet printing techniques. Employing PEDOT:PSS for the p-type legs and a doped fullerene derivative for the n-type ones, we demonstrate a μ-OTEG with power density of 30.5 nW/cm2 under small thermal gradients, proving the concrete possibility of achieving power requirements of low-power, distributed sensing applications. [Display omitted] •Organic materials are attractive for low cost/high throughput thermoelectric generators for IoT and wearable applications.•Most of research so far focused on materials development, while the processes for devices integration lagged behind.•Combination of femtosecond laser machining and inkjet printing allows embedding micro-thermocouples in flexible substrates.•Fully direct written monolithic polymer generators with a power density of 30 nW/cm2 are demonstrated.