Direct and Indirect Exciton Dynamics in Few‐Layered ReS2 Revealed by Photoluminescence and Pump‐Probe Spectroscopy. (27th December 2018)

• Record Type: Journal Article
• Authors: Wang, Xiaofan; Shinokita, Keisuke; Lim, Hong En; Mohamed, Nur Baizura; Miyauchi, Yuhei; Cuong, Nguyen Thanh; Okada, Susumu; Matsuda, Kazunari
• Is Part Of: Advanced functional materials. Volume 29:Number 6(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-12-27
• Subjects: carrier dynamics -- intraband and interband relaxation -- photoluminescence -- pump‐probe spectroscopy -- transition metal dichalcogenides; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201806169
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Atomically thin‐layered ReS2 with a distorted 1 T structure has attracted attention because of its intriguing optical and electronic properties. Here, the direct and indirect exciton dynamics of a three‐layered ReS2 is investigated by polarization‐resolved transient photoluminescence (PL) and ultrafast pump‐probe spectroscopy. The various time scales of the decay signals of the time‐resolved PL (<10 ps), with monitoring of the populations of electron–hole pairs (exciton), and the transient differential reflectance (≈1 and 100 ps), with monitoring of the populations of electrons and/or holes in the excited states, are observed. These results reveal the characteristic exciton dynamics: rapid relaxation of direct excitons (electron–hole pairs) and slow relaxation of the momentum‐mismatched indirect excitons accompanied by a one‐phonon emission process. These findings provide important information regarding the indirect bandgap nature of few‐layered ReS2 and its characteristic exciton dynamics, boosting the understanding of the novel electronic and optical properties of atomically thin‐layered ReS2 . Abstract : New residents of 2D group VI materials, the rhenium dichalcogenides (ReS2 ), are explored by two different transient spectroscopies. Ultrafast direct exciton relaxation (<1 ps) and indirect exciton relaxation (≈100 ps) assisted by the one‐phonon emission process in the indirect bandgap of ReS2 are revealed.