Direct growth Bi2O2Se nanosheets on SiO2/Si substrate for high-performance and broadband photodetector.

Bi2O2Se, a newly emerging two-dimensional (2D) material, has attracted significant attention as a promising candidate for optoelectronics applications due to its exceptional air stability and high mobility. Generally, mica and SrTiO3substrates with lattice matching are commonly used for the growth of high-quality 2D Bi2O2Se. Although 2D Bi2O2Se grown on these insulating substrates can be transferred onto Si substrate to ensure compatibility with silicon-based semiconductor processes, this inevitably introduces defects and surface states that significantly compromise the performance of optoelectronic devices. Herein we employ Bi2Se3as the evaporation source and oxygen reaction to directly grow Bi2O2Se nanosheets on Si substrate through a conventional chemical vapor deposition method. The photodetector based on the Bi2O2Se nanosheets on Si substrate demonstrates outstanding optoelectronics performance with a responsivity of 379 A W-1, detectivity of 2.9 × 1010Jones, and rapid response time of 0.28 ms, respectively, with 532 nm illumination. Moreover, it also exhibits a broadband photodetection capability across the visible to near-infrared range (532-1300 nm). These results suggest that the promising potential of Bi2O2Se nanosheets for high-performance and broadband photodetector applications.

[Protective effects of total epimedium flavonoids against QA-induced toxicity in SH-SY5Y cells].

OBJECTIVE: To investigate the protective effects and its mechanisms of total epimedium flavonoids (TEF) against Quindinince acid (QA)-induced toxicity in SH-SY5Y cells. METHODS: The MT assay was used to detect the toxicity of QA and the cell viability of pretreatment of TEF and co-incubation with QA in SH-SY5Y cells; Cell apoptosis was observed by Hochest33258 staining; SOD and GSH-Px activities as well as MDA content were measured by colorimetric method; The mitochondrial membrane potential (delta psi m) and intracellular free calcium concentration ([Ca2+]i) were monitored by FCM. RESULTS: TEF increased the cell viability of SH-SY5Y cells, reduced apoptosis cells significantly, improved SOD and GSH-Px activities, decreased MDA content, increased the mitochondrial membrane potential and reduced intracellular free calcium concentration( [Ca2+]i ). CONCLUSION: TEF has significant protective effects against QA-induced toxicity in SH-SY5Y cells,the action mechanism may be associated with resisting oxidative stress, decreasing the [Ca2]i and up-regulating delta psi m.

Construction of Bi2O2Se/Bi2Se3 Van Der Waals Heterostructures for Self-Powered and Broadband Photodetectors.

Due to its superior carrier mobility and high air stability, the emerging two-dimensional (2D) layered bismuth oxyselenide (Bi2O2Se) nanosheets have attracted extensive attention, showing great potential for applications in the electronic and optoelectronic fields. However, a high mobility easily leads to a high dark current, seriously restricting optoelectronic applications, especially in the field of photodetectors. In this paper, we report a high-quality Van der Waals (vdWs) Bi2O2Se/Bi2Se3 heterostructure on a fluorophlogopite substrate, exhibiting excellent photodiode characteristics. By means of the effective separation of photogenerated electrons and holes by a junction barrier at the interface, the current on/off ratio is up to about 3 × 103 under 532 nm laser illumination with zero bias. In addition, the photodetector not only achieves a fast response speed of 41 ms but also has a broadband photoresponse from 532 to 1450 nm (visible-NIR). Additionally, the responsivity can reach 0.29 A/W, and the external quantum efficiency exceeds 69% when the device operates in the reverse bias condition. The results indicate that the Bi2O2Se/Bi2Se3 vdWs heterostructure has great potential for self-powered, broadband, and fast photodetection applications.