All-solution-processed scalable and wearable organic thermoelectrics by structurally mimicking transverse thermoelectric effects.

Organic thin-film thermoelectric generators (TEGs) hold great promise as flexible and wearable energy harvesters. However, their broader application is hindered by the difficulty of establishing a temperature gradient within the thin film when using planar heat sources. Here, we introduce pseudo-transverse TEGs (pT-TEGs), an architecture employing an elastic substrate with two thermal conductivities, enabling the orthogonal conversion of longitudinal heat flux into lateral thermovoltage by mimicking the transverse thermoelectric effect. This design circumvents the limitations of conventional thin-film TEGs, such as the need for three-dimensional deformation to form a temperature gradient, allowing efficient thermal energy harvesting from planar heat sources while preserving a two-dimensional form factor. Furthermore, the fully solution-processed and modular pT-TEGs exhibit excellent mechanical flexibility and high scalability. We believe that this approach offers a practical platform for the realization of genuine two-dimensional TEGs and will contribute to the advancement of flexible and wearable energy harvesting technologies.