Low-Temperature Induced Enhancement of Photoelectric Performance in Semiconducting Nanomaterials

Temperature-Dependent Conduction and Photoresponse in Few-Layer ReS2

The electrical behavior and the photoresponse of rhenium disulfide field-effect transistors (FETs) have been widely studied; however, only a few works have investigated the photocurrent as a function of temperature. In this paper, we perform the electrical characterization of few-layer ReS2-based FETs with Cr-Au contacts over a wide temperature range. We exploit the temperature-dependent transfer and output characteristics to estimate the effective Schottky barrier at the Cr-Au/ReS2 interface and to investigate the temperature behavior of parameters, such as the threshold voltage, carrier concentration, mobility, and subthreshold swing. Through time-resolved photocurrent measurements, we show that the photocurrent increases with temperature and exhibits a linear dependence on the incident light power at both low and room temperatures and a longer rise/decay time at higher temperatures. We surmise that the photocurrent is affected by the photobolometric effect and light-induced desorption of adsorbates which are facilitated by the high temperature and the low pressure.

Plasmon driven nanocrystal transformation in low temperature environments

The preparation and modification of crystal structures in cryogenic environments with conventional methods is challenging, but it is essential for the development of composite materials, energy savings, and future human space exploration. Plasmon induced hot carriers and local thermal effects help to overcome the challenges of chemical reactions under extreme conditions, for which molecular reactions have attracted considerable research attention. In this work, the plasmon thermal effect enables fast and efficient nanocrystal transformation in cryogenic environments, which was previously unattainable with conventional heating methods. The transformation of NaYF₄ nanocrystals on gold nanoparticle island films can be achieved even in a low temperature environment of 11 K. Compared with the structure with gold nanoparticles adhered to NaYF₄ nanocrystals directly, the structure of gold nanoparticle island films with an Al₂O₃ layer offered better heat trapping properties, which allows the complete transformation to take place of NaYF₄ nanocrystals into Y₂O₃ nanocrystals in low temperature environments. This work explores the potential of applying the photothermal effect of a plasmon to induce rapid transformation of nanocrystals in extreme environments and provides insight into the process of crystal transformation and growth.

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care-An Updated Review (2018-2021)

Carbon dots (CDs) are usually smaller than 10 nm in size, and are meticulously formulated and recently introduced nanomaterials, among the other types of carbon-based nanomaterials. They have gained significant attention and an incredible interest in the field of nanotechnology and biomedical science, which is merely due to their considerable and exclusive attributes; including their enhanced electron transferability, photobleaching and photo-blinking effects, high photoluminescent quantum yield, fluorescence property, resistance to photo-decomposition, increased electrocatalytic activity, good aqueous solubility, excellent biocompatibility, long-term chemical stability, cost-effectiveness, negligible toxicity, and acquaintance of large effective surface area-to-volume ratio. CDs can be readily functionalized owing to the abundant functional groups on their surfaces, and they also exhibit remarkable sensing features such as specific, selective, and multiplex detectability. In addition, the physico-chemical characteristics of CDs can be easily tunable based on their intended usage or application. In this comprehensive review article, we mainly discuss the classification of CDs, their ideal properties, their general synthesis approaches, and primary characterization techniques. More importantly, we update the readers about the recent trends of CDs in health care applications (viz., their substantial and prominent role in the area of electrochemical and optical biosensing, bioimaging, drug/gene delivery, as well as in photodynamic/photothermal therapy).