Indium [In-111] chloride 370MBq/1ml radiopharmaceutical precursor solution vials

While the shape-dependent quantum confinement (QC) effect in anisotropic semiconductor nanocrystals has been extensively studied, the QC in facet-specified polyhedral quantum dots (QDs) remains underexplored. Recently, tetrahedral nanocrystals have gained prominence in III-V nanocrystal synthesis. In our study, we successfully synthesized well-faceted tetrahedral InAs QDs with a first excitonic absorption extending up to 1700 nm. We observed an unconventional sizing curve, indicating weaker confinement than for equivalently volumed spherical QDs. The (111) surface states of InAs QDs persist at the conduction band minimum state even after ligand passivation with a significantly reduced band gap, which places tetrahedral QDs at lower energies in the sizing curve. Consequently, films composed of tetrahedral QDs demonstrate an extended photoresponse into the short-wave infrared region, compared to isovolume spherical QD films.

Abstract licence: CC BY-NC-ND

Transparent conductive oxides such as indium tin oxide (ITO) are standards for thin film electrodes, providing a synergy of high optical transparency and electrical conductivity. In an electrolytic environment, the determination of an inert electrochemical potential window is crucial to maintain a stable material performance during device operation. We introduce operando ellipsometry, combining cyclic voltammetry (CV) with spectroscopic ellipsometry, as a versatile tool to monitor the evolution of both complete optical (i.e., complex refractive index) and electrical properties under wet electrochemical operational conditions. In particular, we trace the degradation of ITO electrodes caused by electrochemical reduction in a pH-neutral, water-based electrolyte environment during electrochemical cycling. With the onset of hydrogen evolution at negative bias voltages, indium and tin are irreversibly reduced to the metallic state, causing an advancing darkening, i.e., a gradual loss of transparency, with every CV cycle, while the conductivity is mostly conserved over multiple CV cycles. Post-operando analysis reveals the reductive (loss of oxygen) formation of metallic nanodroplets on the surface. The reductive disruption of the ITO electrode happens at the solid-liquid interface and proceeds gradually from the surface to the bottom of the layer, which is evidenced by cross-sectional transmission electron microscopy imaging and complemented by energy-dispersive X-ray spectroscopy mapping. As long as a continuous part of the ITO layer remains at the bottom, the conductivity is largely retained, allowing repeated CV cycling. We consider operando ellipsometry a sensitive and nondestructive tool to monitor early stage material and property changes, either by tracing failure points, controlling intentional processes, or for sensing purposes, making it suitable for various research fields involving solid-liquid interfaces and electrochemical activity.

Abstract licence: CC BY

Biological systems excel in image recognition with low power and fast responses. Inspired by the human eye, researchers have developed solid-state artificial visual systems. In this study, a retinomorphic artificial synapse device based on a tungsten diselenide (WSe2)/indium arsenide quantum dot (InAs QD) heterostructure is developed. This device exhibits enhanced short-wavelength infrared (SWIR) responsivity at 1060 nm, which is a synaptic behavior analogous to the human retina. The WSe2/InAs QD improves charge transport and photon absorption through the quantum confinement effects of InAs QDs, facilitating efficient SWIR detection. The heterojunction enables effective electron-hole pair separation, enhancing the photodetector performance. The device adapts to SWIR signal pulses like the human eye to light flicker. The WSe₂/InAs QD device demonstrates significantly higher responsivity and a superior ability to emulate a wide range of synaptic properties compared to previously reported Si-based and 2D material/QD-based devices. An artificial neural network trained on the Fashion MNIST dataset achieved over 85% accuracy, which is higher than previous reports. This showcases the potential of retina-inspired SWIR optoelectronic devices for compact, efficient machine vision and in-sensor computing. This study underscores the potential of integrating QDs with 2D materials to create advanced photodetectors that mimic biological sensory functions.

Abstract licence: CC BY-NC-ND

Indium phosphide quantum dots (InP QDs) are a promising example of Restriction of Hazardous Substances directive (RoHS)-compliant light-emitting materials. However, they suffer from low quantum yield and instability upon processing under ambient conditions. Colloidal atomic layer deposition (c-ALD) has been recently proposed as a methodology to grow hybrid materials including QDs and organic/inorganic oxide shells, which possess new functions compared to those of the as-synthesized QDs. Here, we demonstrate that ZnO shells can be grown on InP QDs obtained via two synthetic routes, which are the classical sylilphosphine-based route and the more recently developed aminophosphine-based one. We find that the ZnO shell increases the photoluminescence emission only in the case of aminophosphine-based InP QDs. We rationalize this result with the different chemistry involved in the nucleation step of the shell and the resulting surface defect passivation. Furthermore, we demonstrate that the ZnO shell prevents degradation of the InP QD suspension under ambient conditions by avoiding moisture-induced displacement of the ligands from their surface. Overall, this study proposes c-ALD as a methodology for the synthesis of alternative InP-based core@shell QDs and provides insight into the surface chemistry that results in both enhanced photoluminescence and stability required for application in optoelectronic devices and bioimaging.

Abstract licence: CC BY

The synergistic Cu0-Cuδ+ sites are found as the active sites for NH3 synthesis through nitrate electroreduction reaction, but still face significant challenges in stabilizing the Cuδ+ due to its self-reduction. Here we propose an Ohmic contact interface engineering strategy by loading copper nano-islands on indium hydroxide nanocubes. Attributed to the lower work function of Cu than that of In(OH)3 with n-type semiconductor nature, the electrons in Cu can transfer unimpededly to In(OH)3 at the interface of Ohmic junction, triggering and stabilizing polarized Cu0-Cuδ+ active sites. Cu@In(OH)3 sustains both high NH3 yield rate (4.28 mmol h-1 mgcat.-1) and Faradaic efficiency (97.35%) at -0.6 V vs. RHE, while maintaining stability for at least 120 h under an Ampere-level of 800 mA cm-2. Such Ohmic contact interface engineering approach allows for simultaneously constructing and stabilizing the Cu0-Cuδ+ for the electrosynthesis of ammonia, as well as other value-added chemicals relying on above active sites.

Abstract licence: CC BY-NC-ND