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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]

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]

The development of high-performance multispectral photodetector with narrowband and tunable spectral sensitivity is of importance but remains highly challenging to date. Here, we have reported on the fabrication of a Si Au/n-type Si/Au photodetector with tunable narrowband sensitivity not only in ultraviolet but also in near-infrared region, which is related to the controlled charge collection narrowing (CCN) mechanism. What is more, the negative response peak of the device can be readily tuned from 365 to 605 nm, and the positive response peak can be modulated from 938 to 970 nm when the bias varies from 0.1 to −0.1 V. In particular, the full-width at half-maximum is as small as 92 and 117 nm when the negative and positive response peaks approach the ultraviolet short wavelength end and near-infrared long wavelength end, respectively. The opposite polarity of the device responses in ultraviolet-visible and near-infrared regions renders the present Si photodetector potentially important in future multiple band optoelectronic systems. [ABSTRACT FROM AUTHOR]

Due to the wavelength‐dependent absorption, narrow bandgap semiconductors show potential application in ultraviolet (UV) photodetection by thinning. However, the limited absorption in the thinner layer retards their application in high‐performance photodetection. In this paper, the fabrication of an asymmetric Fabry–Pérot (F–P) structure is reported by planar stacking of InSe layer, Al2O3 spacer, and Al back reflector. For the selective absorption enhancement in UV region, the Al2O3 thickness is optimized to be 39 nm by finite element method (FEM). The device presents a peak response at 265 nm illumination, showing the photo‐to‐dark current ratio (Ilight/Idark) of 719. Responsivity (R) and photoconductive gain (G) reach 11.7 A W−1 and 54.7 at the weak light intensity of 0.03 mW cm−2, respectively, which are two orders of magnitude higher than those of the device without the asymmetric F–P structure, revealing the remarkably enhanced absorption. This work shows well compatibility with the manufacturing processes for 2D semiconductor‐based photodetectors and provides a simple and versatile strategy for the application of 2D narrow bandgap semiconductors in high‐performance UV photodetectors. [ABSTRACT FROM AUTHOR]

Superior ultraviolet photodetectors (UVPDs) with fast response speed and high responsivity are essential for UV communication, intelligent sensing, advanced manufacturing, and more. Various studies have demonstrated the excellent performance of traditional UVPDs based on wide bandgap semiconductors (WBSs). However, these devices often suffer from a relatively slow response speed due to the defect states within WBSs. In this work, a new short channel non‐WBS UVPD is developed using the vertically stacked short channel PtSe2/ultrathin‐Si UVPD. The heterojunction is stacked by the 200 nm thick Si flake that exfoliates from a Silicon‐on‐Insulator (SOI) wafer by wet etching and the wafer‐scale CVD ‐grown PtSe2 via the mature PDMS stamp transfer protocols. The absorption in the Si layer, which depends on the incident wavelength, shows a strong correlation with the device photocurrent response. Under 365 nm illumination, the vertical device exhibits a fast UV response speed up to 51.8/73.6 µs. This performance outperforms that of conventional lateral structures and many WBS‐based UVPDs, largely attributed to the extremely short transport distances of photogenerated carriers and the superior physical characteristics of Si. This study shows that ultrathin‐Si is a promising building block for fast speed UVPDs, which are vital for UV optoelectronic applications. [ABSTRACT FROM AUTHOR]