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Ultraviolet photodetectors (UVPDs) which play important roles in military and civil applications are normally fabricated by using wide band gap semiconductors (WBSs) as building blocks. Unfortunately, the commercialization of UVPDs based on WBSs is often limited by their relatively high fabrication cost owing to the use of very complicated growth instruments. In this work, a sensitive UVPD based on non-WBS lead sulfide (PbS) with a relatively small band gap was proposed. Device analysis revealed that the UVPD made of 48.5 nm PbS nanofilm was highly sensitive to UV illumination at 365 nm. Specifically, the responsivity and specific detectivity under 365 nm illumination were 22.25 A W–1 and 4.97 × 1012 Jones, respectively, which are comparable to or better than most of the conventional WBS-based UVPDs. The PbS nanofilm-based UVPD also exhibits excellent environmental stability. Experimental results and simulations based on technology computer-aided design software confirmed that the abnormal properties of PbS nanofilms are related to the relatively thin thickness and wavelength-dependent absorption coefficients. These results open up an opportunity for narrow band gap semiconductors to realize low-cost-sensitive UVPDs in future optoelectronic devices and systems. [ABSTRACT FROM AUTHOR]

We report an unconventional I 2 -catalyzed cascade reaction for the synthesis of angular triquinane derivatives with a fused heterocycle skeleton, leveraging enaminones and anilines as simple acyclic precursors. The key to success lies in I 2 functioning as a polar-reversal catalyst, which alters the reactivity at the α-position of the enaminone and facilitates the first hexa-functionalization of an enaminone along with the formation of highly congested continuous stereocenters.

A facile one-pot synthetic method has been developed for constructing 6- oxa -spiro[4.5]decane skeletons by merging the ring-opening of benzo[ c ]oxepines and formal 1,2-oxygen migration reactions. More than 30 examples of the 6- oxa -spiro[4.5]decane derivatives have been synthesized under transition-metal-free conditions.

A three-component annulation reaction and trifluoromethylation for the construction of 3-(trifluoromethyl)-4 H -pyrans using β-CF 3 -1,3-enynes, BrCF 2 CO 2 Et, and sulfoxonium ylides as readily available substrates has been developed. This metal-free process involves two C-F bond cleavages of β-CF 3 -1,3-enynes and a CF 3 group generated in situ from BrCF 2 CO 2 Et. This method is applicable to the late-stage modification of pharmaceutically active molecules.

A concise and efficient hydrodefluorination process was developed for the synthesis of gem -difluoroalkenes. This reaction employs rongalite as a masked proton source and does not require any additional catalysts or reductants. Notably, trifluoromethyl alkenes having both terminal and internal double bonds are compatible with this process, allowing for a wider range of substrates. The successful late-stage functionalizations of pharmaceuticals and gram-scale syntheses were used to demonstrate the viability of this method.

An unprecedented [1+1+1+1+1+1] annulation process has been developed for the construction of tetrahydro-2 H -thiopyran 1,1-dioxides. Notably, rongalite acted as a tethered C-S synthon in this reaction and can be chemoselectively used as triple C1 units and as a source of sulfone. Mechanistic investigation indicated that two different carbon-increasing models are involved in this reaction in which rongalite serves as C1 units.

Rongalite has been used in several challenging synthetic transformations with operationally simple and effective protocols. However, the employment of multiple characteristics of rongalite in synthetic chemistry is comparatively little known. Herein we report a separate-embedding type sulfonylmethylation of sulfoxonium ylides in which rongalite concurrently acted as a sulfone source, C1 synthon, radical initiator, and potential reducing reagent for the first time. Notably, this facile and easy-handling reaction does not require a catalyst or prefunctionalized sulfonylmethylation reagents.

An efficient rhodium-catalyzed enantioselective arylation of isatin-derived N -Boc ketimines with arylboroxines has been developed using H 8 -BINOL-derived phosphite-olefin as a chiral ligand. This method allows access to a broad variety of valuable tetrasubstituted 3-amino-2-oxindole derivatives in good yields (up to 98%) with excellent enantioselectivities (up to 98% ee).

A rhodium/sulfur-olefin complex catalyzed asymmetric 1,2-addition of arylboronic acids to six-membered 1,2,6-thiadiazinane 1,1-dioxide-type cyclic imines to access highly optically active sulfamides (95-99% ee) has been developed. By taking advantage of the simple functional group transformations, an interesting array of valuable chiral 1,3-diamines with different substitution patterns can be readily obtained in a highly enantioenriched manner.

Fluorination is an effective process to open the band gap of graphene (Gr), which is beneficial to the development of optoelectronic devices working in wide wavelength. Herein, we report a dual-mode broadband photodetector (PD) by integrating fluorinated graphene (F-Gr) with silicon (Si). It is found that when working in photoconductive mode, the F-Gr/Si heterojunction exhibited a remarkable photoresponse over a wide spectral region from ultraviolet (UV), visible to near infrared (NIR) light with a high responsivity ( R) of 1.9 × 10 7 A W -1 and specific detectivity ( D*) of 4.4 × 10 12 Jones at 650 nm. Nonetheless, both parameters will be considerably reduced when the F-Gr/Si heterojunction works in the photodiode mode. In this mode, the I light / I dark ratio is as high as 2.0 × 10 5 and the response speed is accelerated by more than 3 orders of magnitude from about 5 ms to 6.3 μs. Notably, the responsivity of the device in the UV and NIR regions was remarkably enhanced in comparison with that of pristine Gr/Si-heterojunction-based devices. Considering the F-coverage-dependent band gap of the F-Gr revealed by the first-principle calculations, we believe that the enhancement was ascribed to the opening of the band gap in the partially fluorinated Gr, which is stabilized due to the configuration entropy as the temperature increases. The dual-mode PD enabled the simultaneous weak light detection and fast photodetection, which overcome the limitation of the traditional monomode PD.

A site-selective rhodium-catalyzed asymmetric 1,4-/1,2-addition of arylboronic acids to challenging α,β-unsaturated cyclic ketimines was realized through a ligand-controlled strategy. By employing different chiral olefin ligands, a ligand-controlled switch in the reaction regioselectivity was attained for the first time. The reactions allow the synthesis of highly valuable α,α-disubstituted chiral allylic amines and enantioenriched 1,4-adducts. Further product transformation provided easy access to various quaternary carbon-containing chiral amines and amino acid derivatives bearing multifunctional groups.

A rhodium/diene complex catalyzed asymmetric 1,4-addition of arylboronic acids to indole-derived α,β-unsaturated esters to access highly enantioenriched 3-(1H-indol-2-yl)-3-arylpropanoates has been developed. By taking advantage of the nucleophilic character of indole at C3 and N1 positions, construction of a series of valuable chiral tricyclic indole frameworks such as 2,3-dihydro-1H-pyrrolo[1,2-a]indoles and cyclopenta[b]indoles can be efficiently achieved.

Silicon nanostructure-based solar cells have lately intrigued intensive interest because of their promising potential in next-generation solar energy conversion devices. Herein, we report a silicon nanowire (SiNW) array/carbon quantum dot (CQD) core-shell heterojunction photovoltaic device by directly coating Ag-assisted chemical-etched SiNW arrays with CQDs. The heterojunction with a barrier height of 0.75 eV exhibited excellent rectifying behavior with a rectification ratio of 10(3) at ±0.8 V in the dark and power conversion efficiency (PCE) as high as 9.10% under AM 1.5G irradiation. It is believed that such a high PCE comes from the improved optical absorption as well as the optimized carrier transfer and collection capability. Furthermore, the heterojunction could function as a high-performance self-driven visible light photodetector operating in a wide switching wavelength with good stability, high sensitivity, and fast response speed. It is expected that the present SiNW array/CQD core-shell heterojunction device could find potential applications in future high-performance optoelectronic devices.

We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high Ilight/Idark ratio of 2 × 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W(-1) and 1.38 × 10(10) cm Hz(1/2) W(-1), respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.

A new family of organic-inorganic hybrid material of alpha-nickel hydroxide formulated as Ni(OH)2-x(An-)x/n-(C6H12N4)y.zH2O (A=Cl-, CH3COO-, SO4(2-), NO3-; x=0.05-0.18, y=0.09-0.11, z=0.36-0.43) with high stability and adjustable interlayer spacing ranging from 7.21 to 15.12 A has been successfully prepared by a simple hydrothermal method. The effects of various anions and hexamethylenetetramine (HMT) on the d values of alpha-nickel hydroxide have been systematically investigated. This family of hybrid materials is of such high stability that they can stand more than 40 days in 6 M KOH. The product with a formula Ni(OH)1.95(C6H12N4)0.11(Cl-)0.05(H2O)0.36 has a high surface area of about 299.26 m2/g and an average pore diameter of about 45.1 A. The coercivity (Hc) value is ca. 2000 Oe for the sample with a d spacing of 13.14 A. Moreover, the prepared alpha-Ni(OH)2 in our experiment is of high stability in strong alkali solution. Such high stability could be derived from strong chelating interactions between the Ni ions and HMT molecules with the interlayers. This high chemical stability could make this material more suitable for the applications.