Leaf‐Inspired Flexible Thermoelectric Generators with High Temperature Difference Utilization Ratio and Output Power in Ambient Air

The inherently small temperature difference in air environment restricts the applications of thermoelectric generation in the field of Internet of Things and wearable electronics. Here, a leaf‐inspired flexible thermoelectric generator (leaf‐TEG) that makes maximum use of temperature difference by vertically aligning poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate and constantan thin films is demonstrated. Analytical formulae of the performance scales, i.e., temperature difference utilization ratio (φ th) and maximum output power (P max), are derived to optimize the leaf‐TEG dimensions. In an air duct (substrate: 36 °C, air: 6 °C, air flowing: 1 m s−1), the 10‐leaf‐TEG shows a φ th of 73% and P max of 0.38 µW per leaf. A proof‐of‐concept wearable 100‐leaf‐TEG (60 cm2) generates 11 µW on an arm at room temperature. Furthermore, the leaf‐TEG is flexible and durable that is confirmed by bending and brushing over 1000 times. The proposed leaf‐TEG is very appropriate for air convection scenarios with limited temperature differences.
A leaf‐structure thin film‐based flexible thermoelectric generator (leaf‐TEG), structure similar to fins, enhances the temperature difference utilization ratio (φ th) of up to 85% with a rapid response to air temperature fluctuations. Thus opening the path to the development of highly efficient output under limited temperature difference conditions for the flexible TEG field.