Prefer‐Oriented Ag<sub>2</sub>Se Crystal for High‐Performance Thermoelectric Cooling
Feng Jiang, Chenhao Lin, Jinxuan Cheng, Hulei Yu, Yifan Zhou, Xiaojing Ma, Lifu Wu, Sheng Ye, Jiang Chen, Shizhen Zhi, Yao Xu, Peng Zhao, Xiaodong Wang, Feng Cao, Qian Zhang, Jun Mao
Abstract
Abstract Ag 2 Se‐based materials with promising room‐temperature thermoelectric performance have been known for decades. However, thermoelectric cooling devices based on bulk Ag 2 Se have seldom been reported, mainly due to the phase transition ≈400 K poses a grand challenge for leg design and module integration. Herein, Ag 2 Se crystals with the preferred orientation have been prepared. A high carrier mobility of ≈1846 cm 2 V −1 s −1 and a power factor of ≈31.2 µW cm −1 K −2 at room temperature has been realized, and results in a zT of ≈0.95 at 300 K. Importantly, by applying Ag as the contact layer, the Ag/Ag 2 Se/Ag joint has been prepared by one‐step sintering. By maintaining the pressure of ≈10 MPa after sintering and during the reflow soldering, the deleterious effect of the large thermal expansion can be alleviated. The contact resistance of the Ag/Ag 2 Se interface is as low as ≈2.9 µΩ cm 2 , indicating negligible electrical parasitic loss. The thermoelectric device with 7 pairs of Ag 2 Se and (Bi, Sb) 2 Te 3 has been fabricated and it can achieve a maximum cooling power of ≈2.90 W and a cooling temperature difference of ≈70.4 K at the hot‐side temperature of 350 K, demonstrating the great potential of Ag 2 Se for cooling applications.