Excitons in atomically thin 2D semiconductors and their applications

Abstract

The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. In this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical means is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.

Exciton diffusion in monolayer semiconductors with suppressed disorder

“…On the nanoscale, they can form stable structures down to the effective two-dimensional limit of a single monolayer as thin as several angstroms . [9][10][11] The TMDC family was shown to host a rich variety of remarkable properties associated with their peculiar electronic structure, spin-valley locking, strong light-matter interactions, and complex manybody physics , [12][13][14][15] stimulating broad interest across the research community.…”

Probing exciton species in atomically thin WS2–graphene heterostructures

“…Single-layered transition metal dichalcogenides (TMDC) have been observed to exhibit enhanced light-matter interactions granted by their two-dimensional nature which results in strong Coulomb interaction and reduced dielectric screening compared to bulk semiconductors [1,2]. The reduced dimensionality makes it possible for excitons to bind even at room temperature, with binding energy of hundreds of meV [2], and to modulate their emission using several methods, such as light [3,4], electric field [4,5], magnetic field [6], and strain [7]. The ease of emission tunability offers unique advantages in optoelectronics and photonics, such as flexible, ultra-thin LEDs [8], lasers [9,10], as well as valleytronic applications [11].…”

Photoluminescence Study of B‐Trions in MoS2 Monolayers with High Density of Defects

“…The appearance of 2D atomic crystals with various optical and electrical properties has opened up new routes for electronic and optoelectronic device fabrication based on atomically thin layers . Among them, monolayers of transition metal dichalcogenides (TMDs), such as MoSe 2 , WSe 2 , and MoS 2 , are the most attractive having well‐defined semiconductor properties .…”