With speeding up development of 5G chips, high-efficient and precise thermal managements become a substantial challenge to the power-hungry electronics. Classic passive cooling technologies transport heat to the environment by the forced circulation of air or liquid. Electrocaloric cooling, as an advanced solid-state refrigeration technology, utilizes reversible temperature change of the ferroelectric materials during electrical charging-discharging cycles. Thus, it can transport heat in a reversible temperature gradient, and has potential of zero greenhouse effect, high efficiency, and compact device system.
Ferroelectric polymers are flexible and have excellent electrocaloric performance, while they are poor thermal conductors. High electric field is inevitable to driven refrigeration, thus reducing the device stability in long-term service. As a part of the project, i.e. transformative technologies on high-efficient thermal management, which was supported by the national key research & development programof China, the research group of Professor Qun-Dong Shen designed electrocaloric devices making use of an interpenetrating network of ferroelectric polymer and thermal conductive material, and realized a more than 200% increase in the electrocaloric performance, as well as the thermal conductivity.
The electric dipoles in the ferroelectric polymer tend to align along the electric field and release thermal energy. It brings about hot-spots due to poor conductivity of polymer in the presence of random phonon scattering. The 3-D network embedded in the polymer matrix leads to an increase in the number of the manipulable electric dipoles. Thereby, it remarkably reduces the electric energy for switching the orientation of electric dipoles during refrigeration cycles. And mostly important, the continuous network provides a high-speed phonon pathway, enabling rapid transport of thermal energy among cold and hot regions. Consequently, it solves the problem of slow heat dissipation at the interface of polymer and electronic device, ignoring the inherent low thermal conductivity of the polymers. The research group also fabricated a device protype for cooling semiconductor chips, based on the smart electrocaloric composite materials and electromagnetic actuation. It sheds light on the precise thermal management on the fixed-point of the next-generation intelligent microelectronic devices.
The work was published on Nature Communications. The first author is Ming-Ding Li. Professor Xiao-Liang Wang and Jian Li also participated in the research. In recent years, the Shen’s group has focused on the applications of the ferroelectric materials in electronics and medical neuroscience (Adv. Mater. 2020, 32, 2003800; Adv. Funct. Mater. 2020, 30, 1910323; Adv. Mater. 2016, 28, 10684; Adv. Funct. Mater. 2016, 26, 3640).
Title: Thermal Management of Chips by a Device Prototype Using Synergistic Effects of 3-D Heat-Conductive Network and Electrocaloric Refrigeration
Link：https://www.nature.com/articles/s41467-022-33596-z