2D Materials for Large‐Area Flexible Thermoelectric Devices

Abstract

The rapid development of the concept of the “Internet of Things (IoT)” requires wearable devices with maintenance‐free batteries, and thermoelectric energy conversion based on large‐area flexible materials has attracted much attention. Among large‐area flexible materials, 2D materials, such as graphene and related materials, are promising for thermoelectric applications due to their excellent transport properties and large power factors. In this Review, both single‐crystalline and polycrystalline 2D materials are surveyed using the experimental reports on thermoelectric devices of graphene, black phosphorus, transition metal dichalcogenides, and other 2D materials. In particular, their carrier‐density dependent thermoelectric properties and power factors maximized by Fermi level tuning techniques are focused. The comparison of the relevant performances between 2D materials and commonly used thermoelectric materials reveals the significantly enhanced power factors in 2D materials. Moreover, the current progress in thermoelectric module applications using large‐area 2D material thin films is summarized, which consequently offers great potential for the use of 2D materials in large‐area flexible thermoelectric device applications. Finally, important remaining issues and future perspectives, such as preparation methods, thermal transports, device designs, and promising effects in 2D materials, are discussed.

Reduced Fracture Strength of 2D Materials Induced by Interlayer Friction

“…2D layered materials (2DLMs), such as graphene and transition metal dichalcogenides (TMDs), have drawn increasingly more attention owing to their novel physical properties [1][2][3][4][5] and their potential applications as the functional membranes in flexible electronics and nano-electromechanical systems (NEMS). [6][7][8][9] The mechanical properties of 2DLMs play vital roles in mastering the performances and service life of these devices. [10] Since 2DLMs are linked by van der Waals interaction, [11] the interlayer interactions have been suggested to exhibit apparent influence on their mechanical properties.…”

Thermoelectric effect and devices on IVA and VA Xenes

“…Those synthesis methods can be classified into two groups: top-down and bottom-up，as summarized elsewhere. 40,102,103 Here provides a brief overview on most recent updates.…”

“…272,275 Compared with bulk devices, thin film or lowdimensional based thermoelectric generators (TEG) have several advantages: reduction in the use of costly materials 276 ; a wide range of different designs and possible flexibility 277 ; possible integration for on-chip cooling or energy harvesting, 278 etc. For instance, the electrical resistance only increases less than 5% when the bending radius is ≥5 mm, providing a promising wearable thermoelectric application ( Figure 6A); 279 a stretchable temperature sensor can measure temperature precisely with poor strain sensitivity, critical in soft robotics ( Figure 6B); 280 3D helical thermoelectric coils can be formed without compromising the flexibility of 2D materials ( Figure 6C); 103,281 a planar or large area pn junction version of TEG is more CMOS compatible than π-type bulk topology ( Figure 6D,E). 273,282 TEG requires a specific combination of TE material itself, contact materials, bonding layers, the ceramic heat spreader, etc.…”

Engineering 2D Materials: A Viable Pathway for Improved Electrochemical Energy Storage

“…In addition to the improved electron transfer efficiency (e.g., by introducing graphene) as discussed in Section 2.5, the multifunctions are critical in realizing and improving some functional second batteries (e.g., the flexible metal-air and thermoelectric batteries). [237][238][239][240][241][242][243][244][245][246][247][248] The flexibility and the thermal management can be achieved by directly incorporating 2D materials (e.g., graphene and hBN) into the devices, [240,246] so, instead of doing a further discussion on them, we will focus our discussion next on the improved energy storage performance and the newly induced catalysis from the hybrid engineering.…”