Phase engineering of layered anode materials during ion-intercalation in Van der Waal heterostructures.

Transition metal dichalcogenides (TMDs) are a class of 2D materials demonstrating promising properties, such as high capacities and cycling stabilities, making them strong candidates to replace graphitic anodes in lithium-ion batteries. However, certain TMDs, for instance, MoS, undergo a phase transformation from 2H to 1T during intercalation that can affect the mobility of the intercalating ions, the anode voltage, and the reversible capacity. In contrast, select TMDs, for instance, NbS and VS, resist this type of phase transformation during Li-ion intercalation.

Tuning of the electronic and vibrational properties of epitaxial MoSthrough He-ion beam modification.

Atomically thin transition metal dichalcogenides (TMDs), like MoSwith high carrier mobilities and tunable electron dispersions, are unique active material candidates for next generation opto-electronic devices. Previous studies on ion irradiation show great potential applications when applied to two-dimensional (2D) materials, yet have been limited to micron size exfoliated flakes or smaller. To demonstrate the scalability of this method for industrial applications, we report the application of relatively low power (50 keV)Heion irradiation towards tuning the optoelectronic properties of an epitaxially grown continuous film of MoSat the wafer scale, and demonstrate that precise manipulation of atomistic defects can be achieved in TMD films using ion implanters.

Phase evolution and structural modulation during in situ lithiation of MoS, WS and graphite in TEM.

Li-ion batteries function by Li intercalating into and through the layered electrode materials. Intercalation is a solid-state interaction resulting in the formation of new phases. The new observations presented here reveal that at the nanoscale the intercalation mechanism is fundamentally different from the existing models and is actually driven by nonuniform phase distributions rather than the localized Li concentration: the lithiation process is a 'distribution-dependent' phenomena.

Highly efficient Cs-based perovskite light-emitting diodes enabled by energy funnelling.

The incorporation of phenylethylammonium bromide (PEABr) into a fully inorganic CsPbBr perovskite framework led to the formation of mixed-dimensional perovskites, which enhanced the photoluminescence due to efficient energy funnelling and morphological improvements. With a PEABr : CsPbBr ratio of 0.8 : 1, PeLEDs with a current efficiency of 6.