The demands for waste heat energy recovery from industrial production, solar energy, and electronic devices have resulted in increasing attention being focused on thermoelectric materials. Over the past two decades, significant progress is achieved in inorganic thermoelectric materials. In addition, with the proliferation of wireless mobile devices, economical, efficient, lightweight, and bio‐friendly organic thermoelectric (OTE) materials have gradually become promising candidates for thermoelectric devices used in room‐temperature environments. With the development of experimental measurement techniques, the manufacturing for nanoscale thermoelectric devices has become possible. A large number of studies have demonstrated the excellent performance of nanoscale thermoelectric devices, and further improvement of their thermoelectric conversion efficiency is expected to have a significant impact on global energy consumption. Here, the development of experimental measurement methods, theoretical models, and performance modulation for nanoscale OTE materials are summarized. Suggestions and prospects for the future development of these devices are also provided.
A photodetector based on 2D non‐layered materials can easily utilize the photogating effect to achieve considerable photogain, but at the cost of response speed. Here, a rationally designed tunneling heterojunction fabricated by vertical stacking of non‐layered In2S3 and Te flakes is studied systematically. The Te/In2S3 heterojunctions possess type‐II band alignment and can transfer to type‐I or type‐III depending on the electric field applied, allowing for tunable tunneling of the photoinduced carriers. The Te/In2S3 tunneling heterojunction exhibits a reverse rectification ratio exceeding 104, an ultralow forward current of 10−12 A, and a current on/off ratio over 105. A photodetector based on the heterojunctions shows an ultrahigh photoresponsivity of 146 A W−1 in the visible range. Furthermore, the devices exhibit a response time of 5 ms, which is two and four orders of magnitude faster than that of its constituent In2S3 and Te. The simultaneously improved photocurrent and response speed are attributed to the direct tunneling of the photoinduced carriers, as well as a combined mechanism of photoconductive and photogating effects. In addition, the photodetector exhibits a clear photovoltaic effect, which can work in a self‐powered mode.
Two-dimensional van der Waals magnetic crystals have been attracting significant research interest in recent years, and the manipulation of their magnetism is important for understanding their physical property and achieving their actual applications. Here, we systematically studied the manipulation of magnetic properties of a CrTe2 bilayer through in-plane strain and self-intercalation. We found that the magnetic ground state of the CrTe2 bilayer varies from intralayer antiferromagnetic coupling to ferromagnetic coupling and then to interlayer antiferromagnetic coupling when the strain changes from −6% to 4%, which should result from the coupling between intralayer Cr atoms tuned from direct Cr–Cr exchange to indirect Cr–Te–Cr superexchange. The magnetic easy axis of the CrTe2 bilayer varies from the in-plane to the out-of-plane owing to the change of pz orbital occupation from Te atoms near the Fermi level. Moreover, the magnetic ground states of different Cr-intercalated concentrations for the CrTe2 bilayer are all ferromagnetic, and the magnetic easy axis is in-plane, which are different from the intrinsic one. Our results indicate that the magnetic property of the CrTe2 bilayer is sensitive to the in-plane strain and self-intercalation, which provides important guidance for the further magnetic manipulation of the CrTe2 bilayer in theoretical research and application of magnetic strain sensors and spin transistors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.