Anisotropic Thermal Conductive Composite by the Guided Assembly of Boron Nitride Nanosheets for Flexible and Stretchable Electronics

Abstract

Owing to the growing demand for highly integrated electronics, anisotropic heat dissipation of thermal management material is a challenging and promising technique. Moreover, to satisfy the needs for advancing flexible and stretchable electronic devices, maintaining high thermal conductivity during the deformation of electronic materials is at issue. Presented here is an effective assembly technique to realize a continuous array of boron nitride (BN) nanosheets on tetrahedral structures, creating 3D thermal paths for anisotropic dissipation integrated with deformable electronics. The tetrahedral structures, with a fancy wavy shaped cross‐section, guarantee flexibility and stretchability, without the degradation of thermal conductivity during the deformation of the composite film. The structured BN layer in the composites induces a high thermal conductivity of 1.15 W m−1 K−1 in the through‐plane and 11.05 W m−1 K−1 in the in‐plane direction at the low BN fraction of 16 wt%, which represent 145% and 83% increases over the randomly mixing method, respectively. Furthermore, this structured BN composite maintains thermal dissipation property with 50% strain of the original length of composite. Various electronic device demonstrations provide exceptional heat dissipation capabilities, including thin film silicon transistor and light‐emitting diode on flexible and stretchable composite, respectively.

Solid–Liquid Composites for Soft Multifunctional Materials

“…Figure 5B)-unlike the case for traditional rigid inclusions. [141,142,[142][143][144][145] For improving thermal properties, LMs are desirable due to their high thermal conductivities relative to other liquids (see section 3.1) [3,70,85,[146][147][148][149] (c.f. Figure 5D).…”

A high performance wearable strain sensor with advanced thermal management for motion monitoring

“…With the rapid development of modern electronics, in particular with increasing power density and miniaturization of electronic devices, effective heat dissipation of such devices has become a critical limiting factor, because the generated undesirable heat may be concentrated in a specific area in the devices and causes the thermal failure. In an individual device, heat from an electronic component can disturb the nearby ones 55 . To evaluate the heat-dissipating characteristics of the stretchable strain sensors, thermal conductivity of the samples, including the TPU-BNNS film with BNNS contents of 25 wt%, 30 wt%, and 35 wt%, the pure TPU film, and the whole strain sensor, was measured and compared.…”

Flexible and Stretchable Microwave Electronics: Past, Present, and Future Perspective

“…Further investigations on thermally conductive substrates with mechanical flexibility are on-going. [113,114] Promising results have been reported on improving the DC performance of GaN HEMTs. [115] However, whether these thermally improved substrates are suitable for GaN HEMT in microwave applications remains unknown.…”

“…It is noted that research exploring flexible/stretchable substrates suitable for microwave applications are ongoing. [113,166,277,278] Before any breakthrough happens, inventing a strategy to enhance the thermal conductivity of the present flexible substrates may be an alternative route to a suitable solution for this challenge. It is also noted that there have been no demonstrations of stretchable active microwave electronic circuits on any stretchable substrates.…”