Transition metal perovskite chalcogenides are a new class of versatile semiconductors with high absorption coefficient and luminescence efficiency. Polycrystalline materials synthesized by an iodine-catalyzed solid-state reaction show distinctive optical colors and tunable bandgaps across the visible range in photoluminescence, with one of the materials' external efficiency approaching the level of single-crystal InP and CdSe.

Crystalline metal−organic chalcogenolate assemblies are a class of semiconducting hybrid nanomaterials that consist of well-defined arrays of nanostructured inorganic coordination polymers with a supramolecular lattice of organic ligands. Growing crystals of periodic arrays of nanostructured hybrid chalcogenolates at biphasic liquid−liquid interfaces has been used to prepare semiconducting hybrid materials for potential applications in sensing, catalysis, mechanochemistry, organic light-emitting devices, and photovoltaics. However, a distinct lack of a systematic framework for quantifying the relationship between experimental parameters and the structure−function relationship of the prepared materials has been one of the largest hurdles for the emerging field of hybrid chalcogenolates and related hybrid coordination polymer systems.Here we examine the crystallization of silver benzeneselenolate, coined here as mithrene, at a toluene−water interface and demonstrate that silver ion concentration is the critical variable for controlling the morphology of the semiconducting crystals. Confocal microscopy is used to demonstrate that the blue luminescence of the material is robust across all morphologies. The role of metal ion concentration on the structure and morphology of the hybrid chalcogenolate is considered, and the properties of the crystalline and amorphous products are compared. Grazing-incidence wide-angle X-ray scattering is used to demonstrate that the crystallographic phase of the crystals in sparse layers is uniform across all morphologies. The observation of blue luminescence can be used as a reliable proxy for the crystalline phase in future work. The straightforward synthetic preparation for and robust optoelectronic properties of silver benzeneselenolate make it an ideal model system for the development of device and sensor applications leveraging the emerging class of metal−organic chalcogenolates.

Neuromorphic or "brain-like" computation is a leading candidate for efficient, fault-tolerant processing of large-scale data as well as real-time sensing and transduction of complex multivariate systems and networks such as self-driving vehicles or Internet of Things applications. In biology, the synapse serves as an active memory unit in the neural system and is the component responsible for learning and memory. Electronically emulating this element via a compact, scalable technology which can be integrated in a three-dimensional (3-D) architecture is critical for future implementations of neuromorphic processors. However, present day 3-D transistor implementations of synapses are typically based on low-mobility semiconductor channels or technologies that are not scalable. Here, we demonstrate a crystalline indium phosphide (InP)-based artificial synapse for spiking neural networks that exhibits elasticity, short-term plasticity, long-term plasticity, metaplasticity, and spike timing-dependent plasticity, emulating the critical behaviors exhibited by biological synapses. Critically, we show that this crystalline InP device can be directly integrated via back-end processing on a Si wafer using a SiO buffer without the need for a crystalline seed, enabling neuromorphic devices that can be implemented in a scalable and 3-D architecture. Specifically, the device is a crystalline InP channel field-effect transistor that interacts with neuron spikes by modification of the population of filled traps in the MOS structure itself. Unlike other transistor-based implementations, we show that it is possible to mimic these biological functions without the use of external factors (e.g., surface adsorption of gas molecules) and without the need for the high electric fields necessary for traditional flash-based implementations. Finally, when exposed to neuronal spikes with a waveform similar to that observed in the brain, these devices exhibit the ability to learn without the need for any external potentiating/depressing circuits, mimicking the biological process of Hebbian learning.

Silver metal exposed to the atmosphere corrodes and becomes tarnished as a result of oxidation and precipitation of the metal as an insoluble salt. Tarnish has so poor a reputation that the word itself connotes corruption and disrespectability; however, tarnishing is a facile synthetic approach for preparing thin metal-sulfide films on silver or copper metal that might be exploited to prepare more elaborate materials with desirable optoelectronic properties. In this work, we prepare luminescent semiconducting thin films of mithrene, a metal–organic chalcogenolate assembly, by replacing the tarnish-causing atmospheric sulfur source with diphenyl diselenide. Mithrene, or silver benzeneselenolate [AgSePh]∞, is a crystalline solid that contains both an organic supramolecular phase and a two-dimensional inorganic coordination polymer phase. This compound gradually accumulates as the sole product of silver metal corrosion. The chemical reaction is carried out on metallic silver thin films and yields crystalline films with thicknesses ranging from 5 to 100 nm. We use the large-area films (>6 cm2) afforded by this method to measure the optical properties of this compound. The mild-temperature, wafer-scale processing of hybrid chalcogenolate thin films may prove useful in the application of hybrid organic–inorganic materials in semiconductor devices and hierarchical architectures.