2D Crystals in Three Dimensions: Electronic Decoupling of Single‐Layered Platelets in Colloidal Nanoparticles

//2D Crystals in Three Dimensions: Electronic Decoupling of Single‐Layered Platelets in Colloidal Nanoparticles

Optoelectronic properties of 2D crystals are distinct from their bulk counterparts, and advantageous for applications. Band gaps are larger, and sometimes direct, well‐suited for optoelectronic and photocatalytic applications. However, being atomically thin, low density is a bottleneck for quantitative performance. The proposed intercalation of layered materials with short surfactants yields electronically decoupled layers with similar properties as monolayers, but higher cross‐sections. Abstract 2D crystals, single sheets of layered materials, often show distinct properties desired for optoelectronic applications, such as larger and direct band gaps, valley‐ and spin‐orbit effects. Being atomically thin, the low amount of material is a bottleneck in photophysical and photochemical applications. Here, the formation of stacks of 2D crystals intercalated with small surfactant molecules is proposed. It is shown, using first principles calculations, that the very short surfactant methyl amine electronically decouples the layers. The indirect–direct band gap transition characteristic for Group 6 transition metal dichalcogenides is demonstrated experimentally by observing the emergence of a strong photoluminescence signal for ethoxide‐intercalated WSe2 and MoSe2 multilayered nanoparticles with lateral size of about 10 nm and beyond. The proposed hybrid materials offer the highest possible density of the 2D crystals with electronic properties typical of monolayers. Variation of the surfactant’s chemical potential allows fine‐tuning of electronic properties and potentially elimination of trap states caused by defects.

Published in: "Small".

2018-11-07T08:35:19+00:00November 7th, 2018|Categories: Publications|Tags: , |
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