Strategically constructed AlGaN doping barriers for efficient deep ultraviolet light-emitting diodes.

Here, we propose a sandwich-like Si-doping scheme (undoped/Si-doped/undoped) in Al0.6Ga0.4N quantum barriers (QBs) to simultaneously promote the optoelectronic performances and reliability of deep ultraviolet light-emitting diodes (DUV-LEDs). Through experimental and numerical analyses, in the case of DUV-LEDs with conventional uniform Si-doping QB structure, severe operation-induced reliability degradation, including the increase of reverse leakage current (IR) and reduction of light output power (LOP), will offset the enhancement of optoelectronic performances as the Si-doping levels increase to an extent, which hinders further development of DUV-LEDs. According to a transmission electron microscope characterization and a numerical simulation, an improved interfacial quality in multiple quantum wells (MQWs) and more uniform carrier distribution within MQWs are demonstrated for our proposed Si-doping structure in comparison to the uniform Si-doping structure. Consequently, the proposed DUV-LED shows superior wall-plug efficiency (4%), IR at -6 V reduced by almost one order of magnitude, and slower LOP degradation after 168-h 100 mA-current-stress operation. This feasible doping scheme provides a promising strategy for the high-efficiency and cost-competitive DUV-LEDs.

Strategically constructed AlGaN doping barriers for efficient deep ultraviolet light-emitting diodes: erratum.

We present an erratum to our Letter [Opt. Lett.49, 2049 (2024)10.1364/OL.522212]. There is a careless omission of some references because our Letter is longer than the maximum allowed four pages. The missing references and their specific quote location are listed in the following. These corrections do not affect the data plotted in figures, discussion, or conclusion of the original Letter.

Improvement of light extraction efficiency in AlGaInP-based vertical miniaturized-light-emitting diodes via surface texturing.

AlGaInP-based light-emitting diodes (LEDs) suffer from a low external quantum efficiency (EQE), which is mainly restrained by the poor light extraction efficiency. Here, we demonstrate AlGaInP-based vertical miniaturized-LEDs (mini-LEDs) with a porous n-AlGaInP surface using a wet etching process to boost light extraction. We investigated the effects of etching time on the surface morphology of the porous n-AlGaInP surface. We found that as the etching time is prolonged, the density of pores increases initially and decreases subsequently. In comparison with the vertical mini-LED with a smooth n-AlGaInP surface, the vertical mini-LEDs with the porous n-AlGaInP surface reveal improvement in light output power and EQE, meanwhile, without the deterioration of electrical performance. The highest improvement of 38.9% in EQE measured at 20 mA is observed from the vertical mini-LED with the maximum density of the pores. Utilizing a three-dimensional finite-difference time-domain method, we reveal the underlying mechanisms of improved performance, which are associated with suppressed total internal reflection and efficient light scattering effect of the pores.

Nanoimprinted patterned sapphire with silica array for efficient InGaN-based green mini-LEDs.

Here, we propose nanoimprinted patterned sapphire with a silica array (PSSA) with the aim to promote the efficiency of InGaN-based green (∼520 nm) mini-LEDs. According to x-ray diffraction measurements, the threading dislocation density of GaN epitaxial layers grown on nanoimprinted PSSA demonstrates a pronounced reduction compared with the epilayers on the conventional patterned sapphire substrate (PSS). Consequently, a mini-LED on PSSA exhibits a significantly boosted light output power (LOP) in comparison to a mini-LED on PSS. At 10 mA, the LOP of the mini-LED on PSS is 6.0 mW, and this is further improved to 6.8 mW for the mini-LED on PSSA. Moreover, the peak external quantum efficiencies of the mini-LEDs on PSS and PSSA are 41% and 47%, respectively. A three-dimensional (3D) finite-difference time-domain simulation demonstrates that the PSSA contributes enhanced light extraction for photons emitted from the active region. It is also highly feasible to use this nanoimprinted PSSA technology in red and blue mini-LEDs for the realization of full-color displays.

Exploring online consumer behavior on fraudulent energy-saving products.

Purchasing energy-saving products is key for public participation in energy conservation and sustainable development. However, the sale of fraudulent energy-saving products has boomed through online shopping, with little research on these products and consumer demands. This study explored the underlying factors driving consumer purchases of fraudulent energy-saving products and measured their impact on environmental awareness. Sales data for such products from four major online shopping platforms were collected. Results suggested unique demand characteristics from consumers who unknowingly purchase fraudulent energy-saving products, referred to as "hidden energy savers", including a preference for moderately priced products, a desire for straightforward energy-saving explanations, and a tendency to seek multiple additional features, even if they conflict with the core functionality. Perceived installation and usage difficulty significantly influences purchasing behavior. A practical survey of freight companies and individual transporters' demand for freight energy-saving products was conducted as a case study to validate the practical application of this research. This study presents a novel perspective on public energy-saving behavior, aiding in creating true energy-saving products, boosting public energy conservation interest, and reducing the negative impact of fraudulent products on environmental awareness. It also sheds light on hidden consumer needs, guiding the development of authentic energy-saving products.

An electrochemical biosensor to assay Trop-2 of breast cancer cells fabricated by methylene blue-assisted assembly of DNA nanoparticles.

Human trophoblast surface cell antigen 2 (Trop-2) on the tumor cell membrane can not only serve as the target for chemotherapy drugs, but also as a biomarker for typing and prognosis of breast cancer; however, assay of Trop-2 is seriously hampered due to the limitations of available tool. Herein, we have designed and fabricated an electrochemical biosensor for the assay of Trop-2 based on methylene blue (MB)-assisted assembly of DNA nanocomposite particles (DNPs). Specially, the recognition between Trop-2 and its aptamer may activate the primer exchange reaction (PER) on an electrode surface to produce long single-strand DNA (ssDNA) which can be self-assembled into DNPs by electrostatic interaction between negative charged DNA and positive charged and electro-active MB molecules which can also be used to give electrochemical signal. By using this electrochemical biosensor, ultrasensitive detection of tumor cells with high Trop-2 expressions can be conducted, with the limit of detection (LOD) of 1 cell/mL. Moreover, this biosensor can be further used for accurately profiling Trop-2 expression of tumor cells in mouse tissues, suggesting its great potential in the precise definition of breast cancer.

Flexible nanoimprint lithography enables high-throughput manufacturing of bioinspired microstructures on warped substrates for efficient III-nitride optoelectronic devices.

III-nitride materials are of great importance in the development of modern optoelectronics, but they have been limited over years by low light utilization rate and high dislocation densities in heteroepitaxial films grown on foreign substrate with limited refractive index contrast and large lattice mismatches. Here, we demonstrate a paradigm of high-throughput manufacturing bioinspired microstructures on warped substrates by flexible nanoimprint lithography for promoting the light extraction capability. We design a flexible nanoimprinting mold of copolymer and a two-step etching process that enable high-efficiency fabrication of nanoimprinted compound-eye-like Al2O3 microstructure (NCAM) and nanoimprinted compound-eye-like SiO2 microstructure (NCSM) template, achieving a 6.4-fold increase in throughput and 25% savings in economic costs over stepper projection lithography. Compared to NCAM template, we find that the NCSM template can not only improve the light extraction capability, but also modulate the morphology of AlN nucleation layer and reduce the formation of misoriented GaN grains on the inclined sidewall of microstructures, which suppresses the dislocations generated during coalescence, resulting in 40% reduction in dislocation density. This study provides a low-cost, high-quality, and high-throughput solution for manufacturing microstructures on warped surfaces of III-nitride optoelectronic devices.

Choline Oxidase-Integrated Copper Metal-Organic Frameworks as Cascade Nanozymes for One-Step Colorimetric Choline Detection.

Choline is an important factor for regulating human health and is widely present in various foods. In this work, a sensor strategy based on a choline oxidase-integrated copper(II) metal-organic framework with peroxidase-like activity is constructed for one-step cascade detection of choline. The one-step cascade strategy can avoid intermediate product transferring in general multi-step reactions, and the multi-enzyme activities can be well exerted under one condition, thus exhibiting excellent catalytic activity and enhanced stability. In the integrated system, choline is catalyzed by ChOx to produce betaine and H2O2, which eventually got converted to hydroxyl radicals by the peroxidase nanozyme, oxidized the chromogenic substrate ABTS, and produced an observable absorption peak at 420 nm. A new choline detection method was thus established and showed a satisfactory linear relationship at 6-300 µM, which has been used for the choline analysis in milk.