Polarization tunable thermoelectric cooling and electromagnetic shielding in flexible carbon/ferroelectric/thermoelectric hybrid film

Abstract

Exploiting materials with effective heat dissipation and electromagnetic shielding performance is highly desirable for high integration and high-power density electronic devices. Herein, we introduce a flexible carbon/ferroelectric/thermoelectric (i.e., C/FE/TE) hybrid film with layer-by-layered carbon, PZT/PVDF-TrFE, and bismuth telluride alloys (p-type Bi_0.5Sb_1.5Te₃ or n-type Bi₂Te_2.5Se_0.5), it enables us to achieve thermoelectric cooling and electromagnetic shielding concurrently. More importantly, the electrical performance of the thermoelectric layer can be tuned by the polarization of the ferroelectric layer, and the maximum power factors of 12.7 μW cm^-1 K^-2 and 5.3 μW cm^-1 K^-2 are obtained for Bi_0.5Sb_1.5Te₃ and Bi₂Te_2.5Se_0.5, respectively. Using these C/FE/TE hybrid films, we fabricated a radial-shaped flexible thermoelectric cooling device, which showed a net cooling temperature difference of 1.08 K at 300 K. In addition, the impedance mismatch between free space and C/FE/TE induces reflection loss, the bismuth telluride alloys and carbon layers cause conduction loss, while the polarized PZT/PVDF-TrFE, as well as the interfacial polarization between bismuth telluride alloys and PZT/PVDF-TrFE layers leads to polarization loss. Thus, a high electromagnetic shielding performance with a maximum average shielding efficiency of 32.0 dB in the frequency range of 8.2 ∼ 12.4 GHz (i.e., X-band) was also achieved in the C/FE/TE hybrid film.