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In this study, on the fabrication of a flexible wavelength sensor is reported, which is achieved by growing a layer of lead sulfide (PbS) nanofilm on both sides of a polyethylene terephthalate substrate using the chemical bath deposition method, followed by the deposition of two parallel Au interdigital electrodes. Experimental result shows that the photocurrent ratio of the two photodetectors monotonically decreases with increasing wavelength in the range from 265 nm (UV) to 2000 nm (NIR), indicating that the incident light wavelength can be distinguished by the photocurrent ratio. Notably, the as‐constructed wavelength sensor exhibits superior performance compared to most previously reported filter‐less designs, achieving an average absolute error of 11.5 nm and an average relative error of 1.1%. It is also found that the sensor exhibits excellent mechanical flexibility and environmental stability. Furthermore, by introducing the back‐end circuit, real‐time detection of the wavelength of monochromatic light and the peak wavelength of LED light are achieved, with detection errors not exceeding 2.8% and 2.6%, respectively. It is believed that the flexible PbS nanofilm wavelength sensor prepared in this study has potential application in future portable and flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

A novel process using N-benzylhydroxylamine hydrochloride as a "C1N1 synthon" in [2+2+1] cyclization for the construction of 1,2,5-trisubstituted imidazoles has been described for the first time. The key to realizing this process lies in capturing arylamines by in situ generated novel acyl ketonitrone intermediates. Subsequent tautomerization activates the α-C(sp3)–H of N-benzylhydroxylamines, and thus breaks through its inherent reaction mode and achieves N, α-C site-selective cyclization. Furthermore, this method enables scale-up synthesis and late-stage modification of complex molecules. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The conversion of CF3‐alkenes to gem‐difluoroalkenes using reductive cross‐coupling strategy has received much attention in recent years, however, the use of green and readily available reducing salt to mediate these reactions remains to be explored. In this work, a concise construction of gem‐difluoroalkenes, which requires neither a catalyst nor a metal reducing agent, was established. Rongalite, a safe and inexpensive industrial product, was employed as both a radical initiator and reductant. This procedure was compatible with both linear and cyclic diaryliodonium salts, enabling a wide variety of substrates (>70 examples). The utility of this approach was demonstrated through gram‐scale synthesis and efficient late‐stage functionalizations of anti‐inflammatory drugs. [ABSTRACT FROM AUTHOR]

Accurate and quantifiable detection of the specific wavelength is vital in different application scenarios. Herein, a novel self‐driven narrowband photodetector (NB‐PD) based on CH(NH2)2PbBr2.5I0.5 crystal film is employed for building a yellow light intensity meter. By taking advantage of the carrier collection narrowing mechanism, a sensitive NB‐PD with peak response at 580 nm and the full‐width at half‐maximum of 23 nm are successfully achieved. The asymmetric contact electrodes of Ag/Pt allow the device to work without bias. The optoelectronic analysis demonstrates that the NB‐PD achieves a maximum responsivity of 59.89 mA W−1, a fast response speed of 202/331 µs, and a high on/off ratio of 636 at zero bias. Then, through introducing the back‐end circuit, a yellow light intensity meter is constructed with the NB‐PD. The absolute error and relative error of the light meter are estimated to be lower than 0.08 mW cm−2 and 4.22%, respectively, indicating the good capability for the yellow light monitoring. Given the simple device geometry and good performance, the achieved yellow light intensity meter can also be extended to other narrowband light detection system. [ABSTRACT FROM AUTHOR]

In this study, a solution method derived dual‐band photodetector (PD) based on silicon nanowires /PbS nanocrystalline film n–n heterojunction, which exhibits typical bias‐selectable spectral response in both near‐infrared (NIR) and short‐wave infrared (SWIR) bands, is presented. It is found that by adjusting the polarity of the bias voltage, the photoresponse of the device can be switched between three operation modes. The device exhibits high responsivities of 2100 mA W−1 at −0.15 V and 31 mA W−1 at 0 V, respectively, in the NIR region. Remarkably, the maximum responsivity and detectivity under 2000 nm illumination are determined as 290 mA W−1 and 2.4 × 1010 Jones, comparable to or even better than some PbS commercial PDs. The enhanced performance comes from the improved optical absorption and higher efficiency of charge separation and collection owing to the heterojunction geometry. It's also revealed that the bias‐controllable spectral response is attributed to the selectively transportation of photocarriers across the junction barrier. The study demonstrates the capability of detecting two distinct IR regions with the same pixel, which has great potential in future optoelectronic systems for IR imaging applications. [ABSTRACT FROM AUTHOR]

Here, the fabrication of an addressable 8 × 8 photodetector array is reported by combining In2Se3 nanofilm with periodic inverse micropyramid‐Si (PIMP‐Si), which is obtained through colloidal lithography and anisotropic wet etching. Due to the unique configuration and the outstanding light trapping effect, the as‐fabricated heterojunction device presents an excellent self‐powered photoresponse over the broadband wavelength range from 265 to 1300 nm, with a peak sensitivity at ≈810 nm. The responsivity, specific detectivity, and rise/fall time are estimated to be 0.58 A W−1, 1.76 × 1012 Jones, and 5.1/18 µs, respectively, which are competitive in comparison with other devices with similar geometries. Meanwhile, the photodetector array displays a satisfactory pixel‐to‐pixel uniformity, which allows the device to record the full‐color image of "HFUT" with satisfying resolution, revealing the potential application of the PIMP‐Si/In2Se3 heterojunction photodetector array for real‐time red‐green‐blue‐infrared image sensing and video capturing. [ABSTRACT FROM AUTHOR]

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]