Effect of multiple quantum well periods on structural properties and performance of extended short-wavelength infrared LEDs.

We present research on the role of multiple quantum well periods in extended short-wavelength infrared InGaAs/InAsPSb type-I LEDs. The fabricated LEDs consisted of 6, 15, and 30 quantum well periods, and we evaluated the structural properties and device performance through a combination of theoretical simulations and experimental characterization. The strain and energy band offset was precisely controlled by carefully adjusting the composition of the InAsPSb quaternary material, achieving high valence and conduction band offsets of 350 meV and 94 meV, respectively. Our LEDs demonstrated a high degree of relaxation of 94-96 %. Additionally, we discovered that the temperature-dependent dark current characterization attributed to generation-recombination and trap-assign tunneling, with trap-assign tunneling being more dominant at lower current injections. Electroluminescence analysis revealed that the predominant emission mechanism of the LEDs originated from localized exciton and free exciton radiative recombination, which the 30 quantum wells LED exhibited the highest contribution of the localized exciton/free exciton radiative recombination. We observed that increasing the quantum well periods from 6 to 15 led to an increase in the 300 K electroluminescence intensity of the LED. However, extending the quantum well period to 30 resulted in a decline in emission intensity due to the degradation of the epitaxial film quality.

Starch Assisted the ZnS Buffer Layer in Enhancing the Photoluminescence of ZnSe/ZnS:Mn/ZnS Quantum Dots for Detecting E. Coli and MRSA Bacteria Quickly.

In this study, we used a starch paste stabilizer to synthesize ZnSe: Mn/ZnS- Starch and ZnSe/ZnS: Mn/ZnS-starch quantum dot (QDs) in a non-toxic aqueous solvent. The -CH2-OH group of the starch paste promotes dispersibility and improves the compatibility of quantum dots with antibodies, its bonding is observed in the FTIR spectrum. Besides, the Mn-doped ZnS buffer shell with various concentrations (1, 3, 5, 7, and 9%) influence structure, optical, and photoluminescence of QDs properties were investigated in detail. The greatest luminescence intensity is achieved at a molar ratio of 3% Mn2+/Zn2+. Moreover, the ZnS: Mn buffer shell helps to enhance the fluorescence intensity and quantum yield (QY) of the ZnSe/ZnS: Mn/ZnS QDs, which are higher than ZnSe: Mn/ZnS-starch QDs. Through protein A and EDC bridging, ZnSe/ZnS:3%Mn/ZnS- Starch resulted in good signal and sensitivity, with no toxicity to E. coli O157:H7 and MRSA strains.

Electrodeposited Amorphous Tungsten-doped Cobalt Oxide as an Efficient Catalyst for the Oxygen Evolution Reaction.

Thin film of amorphous tungsten-doped cobalt oxide (W:CoO) was successfully grown on a conducting electrode via an electrochemical oxidation process employing a [Co(WS4 )2 ]2- deposition bath. The W:CoO catalyst displays an attractive performance for the oxygen evolution reaction in an alkaline solution. In an NaOH solution of pH 13, W:CoO operates with a moderate onset overpotential of 230 mV and requires 320 mV overpotential to generate a catalytic current density of 10 mA cm-2 . A low Tafel slope of 45 mV decade-1 was determined, indicating a rapid O2 -evolving kinetics. The as-prepared W:CoO belongs to the best cobalt oxide-based catalysts ever reported for the oxygen evolution (OER) reaction.