Direct Band Gap in Multilayer Transition Metal Dichalcogenide Nanoscrolls with Enhanced Photoluminescence

Ci Lin, Liang Cai, Jui-Han Fu, Shahid Sattar, Qingxiao Wang, Yi Wan, Chien-Chih Tseng, Chih-Wen Yang, Areej Aljarb, Ke Jiang, Kuo-Wei Huang, Lain-Jong Li, Carlo Maria Canali, Yumeng Shi, Vincent Tung

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

A direct band gap that solely exists in monolayer semiconducting transition metal dichalcogenides (TMDs) endows strong photoluminescence (PL) features, whereas multilayer TMD structures exhibit quenched PL due to the direct-to-indirect band gap transition. We demonstrate multilayer TMD (such as MoS2 and WS2) nanoscrolls with a preserved direct band gap fabricated by an effective and facile method of solvent-driven self-assembly. The resultant multilayer nanoscrolls, exhibiting up to 11 times higher PL intensity than the remanent monolayer, are carefully characterized using PL spectroscopy. Significantly enlarged interlayer distances and modulated interlayer coupling in the fabricated nanostructures are unveiled by cross-sectional scanning transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The preservation of direct band gap features is further evidenced by density functional theory calculations using the simplified bilayer model with an experimentally obtained 15 Å interlayer distance. The modulation of the PL intensity as an indicator of the band gap crossover in the TMD nanoscrolls is demonstrated by removing the acetone molecules trapped inside the interlayer space. The general applicability of the method presents an opportunity for large-scale fabrication of a plethora of multilayer TMD nanoscrolls with direct band gaps.
Original languageEnglish (US)
Pages (from-to)1547-1555
Number of pages9
JournalACS Materials Letters
DOIs
StatePublished - Jul 20 2022

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