The influence of the Schottky contact is studied for hole transport material (HTM) free CH₃NH₃PbI₃ perovskite solar cells (PSCs), by using drift-diffusion and small signal models. The basic current-voltage and capacitance-voltage characteristics are simulated in reasonable agreement with experimental data. The build in potential of the finite CH₃NH₃PbI₃ layer is extracted from a Mott-Schottky capacitance analysis. Furthermore, hole collector conductors with work-functions of more than 5.5 eV are proposed as solutions for high efficiency HTM-free CH₃NH₃PbI₃ PSCs.

The emerged wurtzite (wz) Al_1−xB_xN alloy has drawn increasing attention due to its superior ferroelectricity and excellent compatibility with microelectronics. We find that the stability and ferroelectric switching pathways of wz-Al_1−xB_xN alloys are affected by the orbital contribution, covalent bond strength, and elastic constant C₁₄. As the concentration of B increases, the internal parameter u decreases while the elastic constant C₁₄ increases, leading to an increase in spontaneous polarization and a decrease in the polarization switching barrier. The spontaneous polarization, polarization switching barrier, and band gap of wz-Al_1−xB_xN alloy can be further improved through the application of strain in a specific direction, resulting in a giant ferroelectricity. Additionally, the phase transformation of the wz-Al_1−xB_xN alloy induced by the increasing B composition can be regarded as a sequential process involving shrinkage, rotation, and deformation of tetrahedron. These findings give a deep understanding of the ferroelectric wz-Al_1−xB_xN alloy, and provide a guideline for designing a high-performance ferroelectric wz-Al_1−xB_xN alloy.

<!-- *** Custom HTML *** --> Perovskite-based solar cells (PSCs) have opened the possibility of cost-effective, high-efficiency photovoltaic conversion. However, their instabilities prevent them from commercialization. One of the instability triggers has been attributed to the mobile ions flowing into the carrier transport layer(s). To study the effect of this ionic migration, a numerical PSC model is developed, considering electronic and ionic mixed drift-diffusion transport both in the perovskite and the hole transport layer. The inverted PSC architecture, phenyl-C61-butyric acid methyl ester (PCBM)/perovskite/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with two heterojunctions, is analyzed. The effect of the ionic migration on the performance of the PSCs has been analyzed by (1) the variation of the ionic mobile concentration and (2) the modification of the local trapping density. The current–voltage (J–V) and capacitance–voltage characteristics show that the electric field in the bulk can be screened by the ionic distribution modifying the effective built-in voltage. At high ionic concentrations, the electric field at the interfaces is also affected, hindering the charge extraction. The simulations show that the short circuit current is therefore strongly modified.

The giant magnetoimpedance effect of multilayered thin films under stress has great application prospects in magnetic sensing, but related studies are rarely reported. Therefore, the giant magnetoimpedance effects in multilayered thin film meanders under different stresses were thoroughly investigated. Firstly, multilayered FeNi/Cu/FeNi thin film meanders with the same thickness were manufactured on polyimide (PI) and polyester (PET) substrates by DC magnetron sputtering and MEMS technology. The characterization of meanders was analyzed by SEM, AFM, XRD, and VSM. The results show that multilayered thin film meanders on flexible substrates also have the advantages of good density, high crystallinity, and excellent soft magnetic properties. Then, we observed the giant magnetoimpedance effect under tensile and compressive stresses. The results show that the application of longitudinal compressive stress increases the transverse anisotropy and enhances the GMI effect of multilayered thin film meanders, while the application of longitudinal tensile stress yields the opposite result. The results provide novel solutions for the fabrication of more stable and flexible giant magnetoimpedance sensors, as well as for the development of stress sensors.

The four-quadrant detector (4QD), as a highly sensitive and fast-response position-sensitive device, is widely used in laser guidance, target tracking, and related fields. However, traditional visible and infrared 4QDs exhibit significant vulnerability to ambient light interference, particularly under high-intensity background illumination. To address this issue, this paper presents a solar-blind ultraviolet (UV) 4QD and a spot positioning system based on AlGaN diodes, achieving a UV/visible suppression ratio of 2.17 × 10⁴ (without solar-blind filters). The system employs a high-linearity, low-noise capacitive transimpedance amplifier (CTIA) as the readout circuit for the high-sensitivity and rapid-response solar-blind UV detectors, enabling the precise conversion of weak photocurrent signals into voltage signals for digitization. Utilizing a third-order polynomial least-squares fitting algorithm without introducing complex filtering techniques, the system achieves a maximum positioning error of 0.0101 mm and a root-mean-square error (RMSE) of 0.0057 mm, among of one the best-performing solar-blind UV 4QDs. The experimental results demonstrate exceptional spot positioning performance under a 275 nm laser source, meeting the high-precision requirements for space target detection. This research provides a reference for the application of solar-blind UV 4QDs in positioning, alignment, and monitoring scenarios, thereby holding significant practical implications.