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arXiv · 1811.05238

Two dimensional crystals in three dimensions: electronic decoupling of single-layered platelets in colloidal nanoparticles

Roman Kempt·Agnieszka Kuc·Jae Hyo Han·Jinwoo Cheon·Thomas Heine
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Abstract

Two-dimensional crystals, single sheets of layered materials, often show distinct properties desired for optoelectronic applications, such as larger and direct band gaps, valley- and spinorbit effects. Being atomically thin, the low amount of material is a bottleneck in photophysical and photochemical applications. Here, we propose the formation of stacks of two-dimensional crystals intercalated with small surfactant molecules. We show, using first principles calculations, that already the very short surfactant methyl amine electronically decouples the layers. We demonstrate the indirect-direct band gap transition characteristic for Group 6 transition metal dichalcogenides 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 two-dimensional crystals with electronic properties typical for monolayers. Variation of the surfactant's chemical potential allows fine-tuning of electronic properties and potentially elimination of trap states caused by defects.

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Roman Kempt, Agnieszka Kuc, Jae Hyo Han, Jinwoo Cheon, Thomas Heine. 2018-11-13. Two dimensional crystals in three dimensions: electronic decoupling of single-layered platelets in colloidal nanoparticles. https://doi.org/10.1002/smll.201803910

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