Giant photoluminescence enhancement in tungsten-diselenide–gold plasmonic hybrid structures

Abstract

Impressive properties arise from the atomically thin nature of transition metal dichalcogenide two-dimensional materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices. Typical photoluminescence enhancement from transition metal dichalcogenides is 100-fold, with recent enhancement of 1,000-fold achieved by simultaneously enhancing absorption, emission and directionality of the system. By suspending WSe2 flakes onto sub-20-nm-wide trenches in gold substrate, we report a giant photoluminescence enhancement of ∼20,000-fold. It is attributed to an enhanced absorption of the pump laser due to the lateral gap plasmons confined in the trenches and the enhanced Purcell factor by the plasmonic nanostructure. This work demonstrates the feasibility of giant photoluminescence enhancement in WSe2 with judiciously designed plasmonic nanostructures and paves a way towards the implementation of plasmon-enhanced transition metal dichalcogenide photodetectors, sensors and emitters.

Light–matter interaction in transition metal dichalcogenides and their heterostructures

“…The high absorbance values underline the strong light matter interaction of SC-TMDs even in the monolayer limit with a thickness of less than 1 nm as it has been reported by several theoretical and experimental studies, too [14,22,26,27,[45][46][47][48]122,124,128,130] . The sizeable reduction of the absorbance for monolayers on a substrate points to the fact that the optical response can be significantly altered just by modification of substrate or environment by dielectric engineering and screening effects [38,62,63,65,74,89,127,[131][132][133] . The strong influence of the environment on the light-matter interaction of atomically thin semiconducting membranes motivates a great potential not only for sensing applications, but also for novel device architectures with precisely tailorable optical properties.…”

Plasmonic Enhancement and Manipulation of Optical Nonlinearity in Monolayer Tungsten Disulfide

“…Such advantages have been recognized immediately after the inception of monolayer TMDCs as an emerging 2D photonic materials . Recently, enhancements in PL, energy transfer, and SHG from monolayer TMDCs have been realized by near‐field coupling with gold (Au) and silver (Ag) plasmonic structures. In this work, we report on 2D plasmonic enhancement and manipulation of SHG by surface plasmon polariton (SPP) modes confined in planar plasmonic resonators comprised of 2D nanogroove gratings with subwavelength pitch on atomically smooth, single‐crystalline Ag plates .…”

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

“…[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. [37][38][39][40] For example, gap plasmons have been used in different areas, such as enhancing local chemical reactions, [41] dielectric gratings, [42,43] plasmonic nanocavities, [44][45][46] and PL of single layer WSe 2 .…”

“…[37][38][39][40] For example, gap plasmons have been used in different areas, such as enhancing local chemical reactions, [41] dielectric gratings, [42,43] plasmonic nanocavities, [44][45][46] and PL of single layer WSe 2 . [31] One way to generate gap plasmons is to deposit metal particles on metal substrates or films, forming strongly localized plasmonic fields in the gap between the metal substrate and metal particles. Additionally, energetic electrons and holes could also be generated in the junction region, which may have applications in plasmon-mediated photocatalysis.…”