Helical dislocation-driven plasticity and flexible high-performance thermoelectric generator in α-Mg3Bi2 single crystals
Mingyuan Hu, Jianming Yang, Yan Wang, Junchao Xia, Quan Gan, Shuhuan Yang, Juping Xu, Shulin Liu, Wen‐Jin Yin, Baohai Jia, Lin Xie, Haifeng Li, Jiaqing He
Abstract
Inorganic plastic semiconductors play a crucial role in the realm of flexible electronics. In this study, we present a cost-effective plastic thermoelectric semimetal magnesium bismuthide (α-Mg3Bi2), exhibiting remarkable thermoelectric performance. Bulk single-crystalline α-Mg3Bi2 exhibits considerable plastic deformation at room temperature, allowing for the fabrication of intricate shapes such as the letters “SUSTECH” and a flexible chain. Transmission electron microscopy, time-of-flight neutron diffraction, and chemical bonding theoretic analyses elucidate that the plasticity of α-Mg3Bi2 stems from the helical dislocation-driven interlayer slip, small-sized Mg atoms induced weak interlayer Mg-Bi bonds, and low modulus of intralayer Mg2Bi22- networks. Moreover, we achieve a power factor value of up to 26.2 µW cm-1 K-2 along the c-axis at room temperature in an n-type α-Mg3Bi2 crystal. Our out-of-plane flexible thermoelectric generator exhibit a normalized power density of 8.1 μW cm-2 K-2 with a temperature difference of 7.3 K. This high-performance plastic thermoelectric semimetal promises to advance the field of flexible and deformable electronics. The authors find that the plasticity of magnesium bismuthide (α-Mg3Bi2) arises from helical dislocation-driven interlayer slip, and the dispersion of lightweight Mg atoms also plays a pivotal role in facilitating strain redistribution during plastic deformation.