Facilitating Uniform Large-Scale MoS, WS Monolayers, and Their Heterostructures through van der Waals Epitaxy.

The fabrication process for the uniform large-scale MoS, WS transition-metal dichalcogenides (TMDCs) monolayers, and their heterostructures has been developed by van der Waals epitaxy (VdWE) through the reaction of MoCl or WCl precursors and the reactive gas HS to form MoS or WS monolayers, respectively. The heterostructures of MoS/WS or WS/MoS can be easily achieved by changing the precursor from WCl to MoCl once the WS monolayer has been fabricated or switching the precursor from MoCl to WCl after the MoS monolayer has been deposited on the substrate. These VdWE-grown MoS, WS monolayers, and their heterostructures have been successfully deposited on Si wafers with 300 nm SiO coating (300 nm SiO/Si), quartz glass, fused silica, and sapphire substrates using the protocol that we have developed.

Ion-driven nanograin formation in early-stage degradation of tri-cation perovskite films.

The operational stability of organic-inorganic halide perovskite based solar cells is a challenge for widespread commercial adoption. The mobility of ionic species is a key contributor to perovskite instability since ion migration can lead to unfavourable changes in the crystal lattice and ultimately destabilisation of the perovskite phase. Here we study the nanoscale early-stage degradation of mixed-halide mixed-cation perovskite films under operation-like conditions using electrical scanning probe microscopy to investigate the formation of surface nanograin defects.

Overcoming Nanoscale Inhomogeneities in Thin-Film Perovskites via Exceptional Post-annealing Grain Growth for Enhanced Photodetection.

Antisolvent-assisted spin coating has been widely used for fabricating metal halide perovskite films with smooth and compact morphology. However, localized nanoscale inhomogeneities exist in these films owing to rapid crystallization, undermining their overall optoelectronic performance. Here, we show that by relaxing the requirement for film smoothness, outstanding film quality can be obtained simply through a post-annealing grain growth process without passivation agents.

Molecular Weight Tuning of Organic Semiconductors for Curved Organic-Inorganic Hybrid X-Ray Detectors.

Curved X-ray detectors have the potential to revolutionize diverse sectors due to benefits such as reduced image distortion and vignetting compared to their planar counterparts. While the use of inorganic semiconductors for curved detectors are restricted by their brittle nature, organic-inorganic hybrid semiconductors which incorporated bismuth oxide nanoparticles in an organic bulk heterojunction consisting of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C71 butyric acid methyl ester (PC BM) are considered to be more promising in this regard. However, the influence of the P3HT molecular weight on the mechanical stability of curved, thick X-ray detectors remains less well understood.

Enhancing and quantifying spatial homogeneity in monolayer WS.

Controlling the radiative properties of monolayer transition metal dichalcogenides is key to the development of atomically thin optoelectronic devices applicable to a wide range of industries. A common problem for exfoliated materials is the inherent disorder causing spatially varying nonradiative losses and therefore inhomogeneity. Here we demonstrate a five-fold reduction in the spatial inhomogeneity in monolayer WS, resulting in enhanced overall photoluminescence emission and quality of WS flakes, by using an ambient-compatible laser illumination process.

Multi-scale characterisation of a ferroelectric polymer reveals the emergence of a morphological phase transition driven by temperature.

Ferroelectric materials exhibit a phase transition to a paraelectric state driven by temperature - called the Curie transition. In conventional ferroelectrics, the Curie transition is caused by a change in crystal symmetry, while the material itself remains a continuous three-dimensional solid crystal. However, ferroelectric polymers behave differently.

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures.

Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic-inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation, and their effects on charge extraction both at the nano- and macroscale. Here, we have studied the dynamic electrical response of Cs(FAMA)PbIBr perovskite structures by employing conventional and microsecond time-resolved open-loop Kelvin probe force microscopy (KPFM).

3D Magnetic Field Reconstruction Methodology Based on a Scanning Magnetoresistive Probe.

The present work provides a detailed description on quantitative 3D magnetic field reconstruction using a scanning magnetoresistance microscopy setup incorporating a 19.5 μm × 2.5 μm magnetoresistive sensor.