A Flexible Micro‐Thermoelectric Generator Sticker with Trapezoidal‐Shaped Legs for Large Temperature Gradient and High‐Power Density

Micro-thermoelectric generators (m-TEGs) are considered one of the potential semi-permanent power sources for portable self-powered electronic devices. To supply a sufficient amount of power for applications, the m-TEG needs high-performance thermoelectric materials as well as a large temperature difference across the device. Here, an m-TEG with a new device structure, fabricated with a thin polymer-supporting layer and trapezoidal-shaped thermoelectric legs is presented. The m-TEG, in the form of a sticker, is also flexible and can be attached anywhere that requires power. An m-TEG with a step height of 200 mu m is fabricated by sputtering a (Bi, Te)-based thermoelectric material, and the device structure is completed using various challenging device fabrication techniques. The thermoelectric legs in the resulting structure have a very small cross-section area, which enables the m-TEG to have a larger thermal resistance than the conventional structure. This allows creating a larger temperature gradient across the thermoelectric legs. The fabricated m-TEG exhibits a temperature difference as large as 0.90 degrees C, and generates an excellent output power density of 14.37 nW cm(-2)even under natural convection, when attached to a heat source of 48 degrees C.