In this work, an AlGaN-based Deep-Ultraviolet Light-Emitting Diode structure has been designed and simulated for the zincblende and wurtzite approaches, where the polarization effect is included. DFT analysis was performed to determine the band gap direct-to-indirect cross-point limit, AlN carrier mobility, and activation energies for p-type dopants. The multiple quantum wells analysis describes the emission in the deep-ultraviolet range without exceeding the direct-to-indirect bandgap cross-point limit of around 77% of Al content. Moreover, the quantum-confined Stark effect on wavefunctions overlapping has been studied, where Al-graded quantum wells reduce it. Both zincblende and wurtzite have improved electrical and optical characteristics by including a thin AlGaN with low Al content. Mg and Be acceptor activation energies have been calculated at 260 meV and 380 meV for Be and Mg acceptor energy, respectively. The device series resistance has been decreased by using Be instead of Mg as the p-type dopant from 3 kΩ to 0.7 kΩ.

A solar cell structure with a graded bandgap absorber layer based on InGaN has been proposed to overcome early predicted efficiency. Technological issues such as carrier concentration in the p- and n-type are based on the data available in the literature. The influence of carrier concentration-dependent mobility on the absorber layer has been studied, obtaining considerable improvements in efficiency and photocurrent density. Efficiency over the tandem solar cell theoretical limit has been reached. A current density of 52.95 mA/cm², with an efficiency of over 85%, is determined for a PiN structure with an InGaN step-graded bandgap absorption layer and 65.44% of power conversion efficiency for the same structure considering piezoelectric polarization of fully-strained layers and interfaces with electron and hole surface recombination velocities of 10⁻³ cm/s.

The scientific community has been interested in lophine’s versatility and usage in various applications. Research has shown that humic acid is a material that exhibits interference with lophine. Humic molecules associate with each other in supramolecular conformations through weak hydrophobic interactions at alkaline or neutral pH and hydrogen bonds at low pH. This work presents the characterization of a sensitive lophine layer based on water’s hydrogen ions (pH). We conducted a spectroscopy study to analyze how the absorbance at different amounts of lophine depends on pH. This study demonstrates the hyperchromic behavior of imidazole at various pH values, which may be utilized in an intrinsic fiber optic pH sensor. The dynamic range of the fiber optic sensor was 5 to 11.3 pH units. The sensor was developed by coating a thinned fiber with a sensitive lophine layer. It achieves a sensitivity of 0.27 dB/pH and a response time of 5 s.

The journal retracts the article titled “Numerical Study of a Solar Cell to Achieve the Highest InGaN Power Conversion Efficiency for the Whole In-Content Range”