Functional Polyelectrolyte Nanospaced MoS₂ Multilayers for Enhanced Photoluminescence

Abstract

Molybdenum disulfide (MoS2) multilayers with functional polyelectrolyte nanospacing layers are presented. Taking advantage of the facile method of layer-by-layer (LbL) assembly, individual chemically exfoliated MoS2 layers are not only effectively isolated from interlayer coupling but also doped by functional polymeric layers. It is clearly demonstrated that MoS2 nanosheets separated by polymeric trilayers exhibit a much larger increase in photoluminescence (PL) as the number of layers is increased. The enhanced PL has been correlated to the ratio of excitons to trions with the type of polymeric spacers. Because uniform heterogeneous interfaces can be formed between various transition metal dichalcogenides and other soft materials, LbL assembly offers possibilities for further development in the solution-processable assemblies of two-dimensional materials.

Poly(4-styrenesulfonate)-induced sulfur vacancy self-healing strategy for monolayer MoS2 homojunction photodiode

“…The prominent A exciton peak could be further evolved into exciton (X 0 ; ∼1.86 eV; green) and trion (X − ; ∼1.82 eV; blue) peaks. A negative trion is a quasiparticle composed of two electrons and a hole and formed through binding a neutral excition (a photogenerated electron–hole pair) to an electron, the process consumes energy of ∼40 meV (refs 8, 16, 17). By analysing the exciton peaks of the trion (X − ) and exciton (X 0 ), it explicitly manifests that the trion intensity is independent of PSS-induced SVSH (Fig.…”

“…However, 2D materials obtained from this approach is only suitable for fabricating vertical homojunctions which always suffer from large contact resistance7. On the other hand, surface transfer doping is induced by strong electron-donating or withdrawing chemical species attachment on the 2D materials to achieve an effective coupling8. A significant limitation for surface transfer doping is the presence of inert dangling bond-free surface on 2D materials, which will reduce the doping efficiency of dopants9.…”

Gap plasmon-enhanced photoluminescence of monolayer MoS 2 in hybrid nanostructure

“…However, due to the inherent monolayer thickness (about 1 nm), monolayer MoS 2 suffers low PL efficiency and low quantum yield. [17] To compensate for this, different kinds of approaches to enhancing the emission of monolayer MoS 2 are proposed, including chemical doping, [18] polymeric nano-spacing, [19] defect engineering, [20] and using surface plasmon polaritons (SPPs). [21][22][23] Among these methods, SPPs which have been widely utilized for strong light-matter interaction applications such as photoluminescence enhancement [24][25][26][27][28][29][30][31] and surface enhanced Raman scattering, [32,33] could induce hot electrons and cause the phase transition of MoS 2 , [34][35][36] resulting in the enhanced PL in a metal-MoS 2 coupled system.…”

A layer-by-layer assembled MoS2 thin film as an efficient platform for laser desorption/ionization mass spectrometry analysis of small molecules

“…The MoS 2 nanoflakes were then immobilized on a chemically-functionalized substrate to materialize a chip-based LDI-MS platform. 27 The LDI-MS efficiency of [MoS 2 nanoflake] n films, where n indicates the number of LBL assembly cycles, was optimized with LBL assembly of MoS 2 and polyallylamine hydrochloride (PAAH) by controlling the laser energy absorption capacity of the MoS 2 films (Fig. 1).…”