Graded-Band-Gap Zinc–Tin Oxide Thin-Film Transistors with a Vertically Stacked Structure for Wavelength-Selective Photodetection

Filter-free wavelength-selective photodetectors have garnered significant attention due to the growing demand for smart sensors, artificial intelligence, the Internet of Everything, and so forth. However, the challenges associated with large-scale preparation and compatibility with complementary metal-oxide-semiconductor (CMOS) technology limit their wide-ranging applications. In this work, we address the challenges by constructing vertically stacked graded-band-gap zinc–tin oxide (ZTO) thin-film transistors (TFTs) specifically designed for wavelength-selective photodetection. The ZTO thin films with various band gaps are fabricated via atomic layer deposition (ALD) by varying the ALD cycle ratios of zinc oxide (ZnO) and SnO2. The ZTO film with a small Sn ratio exhibits a decreased band gap, and the resultant TFT shows a degraded performance, which can be attributed to the Sn4+ dopant introducing a series of deep-state energy levels in the ZnO band gap. As the ratio of Sn increases further, the band gap of the ZTO also increases, and the mobility of the ZTO TFT increases up to 30 cm2/V s, with a positive shift of the threshold voltage. The photodetectors employing ZTO thin films with distinct band gaps show different spectral responsivities. Then, vertically stacked ZTO (S-ZTO) thin films, with gradient band gaps increasing from the bottom to the top, have been successfully deposited using consecutive ALD technology. The S-ZTO TFT shows decent performance with a mobility of 18.4 cm2/V s, a threshold voltage of 0.5 V, an on–off current ratio higher than 107, and excellent stability under ambient conditions. The resultant S-ZTO TFT also exhibits obviously distinct photoresponses to light at different wavelength ranges. Furthermore, a device array of S-ZTO TFTs demonstrates color imaging by precisely reconstructing patterned illuminations with different wavelengths. Therefore, this work provides CMOS-compatible and structure-compact wavelength-selective photodetectors for advanced and integrable optoelectronic applications

Two new labdane diterpenoids from aerial parts of <i>Leonurus japonicus</i> and their anti-inflammatory activity

<p>Two new labdane diterpenoids, Leojaponin E (<b>1</b>) and F (<b>2</b>), together with three known compounds were isolated from the dried herb of <i>Leonurus japonicus</i> Houtt., Lamiaceae. Their structures were determined based on extensive spectroscopic analyses. The absolute configurations of <b>1</b> and <b>2</b> were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. In addition, compounds <b>1</b> and <b>2</b> exerted inhibition of LPS-induced PGE₂ production in a dose-dependent manner at concentrations ranging from 5 to 20 μM.</p

Atomic Layer Deposition of Nickel on ZnO Nanowire Arrays for High-Performance Supercapacitors

A novel hybrid core–shell structure of ZnO nanowires (NWs)/Ni as a pseudocapacitor electrode was successfully fabricated by atomic layer deposition of a nickel shell, and its capacitive performance was systemically investigated. Transmission electron microscopy and X-ray photoelectron spectroscopy results indicated that the NiO was formed at the interface between ZnO and Ni where the Ni was oxidized by ZnO during the ALD of the Ni layer. Electrochemical measurement results revealed that the Ti/ZnO NWs/Ni (1500 cycles) electrode with a 30 nm thick Ni–NiO shell layer had the best supercapacitor properties including ultrahigh specific capacitance (∼2440 F g^–1), good rate capability (80.5%) under high current charge–discharge conditions, and a relatively better cycling stability (86.7% of the initial value remained after 750 cycles at 10 A g^–1). These attractive capacitive behaviors are mainly attributed to the unique core–shell structure and the combined effect of ZnO NW arrays as short charge transfer pathways for ion diffusion and electron transfer as well as conductive Ni serving as channel for the fast electron transport to Ti substrate. This high-performance Ti/ZnO NWs/Ni hybrid structure is expected to be one of a promising electrodes for high-performance supercapacitor applications