Spectral Characteristics of Noble Metal Nanoparticle–Molybdenum Disulfide Heterostructures

Abstract

near-fi elds and optical absorption [29][30][31] to improve light emission from MoS 2 despite plasmon-phonon coupling, [ 32 ] hot electron transport, [ 33 ] and recombination limitations. Gold (Au) nanoparticle-induced electric fi elds were reported to increase photoluminescence (PL) of MoS 2 1.7-to 2-fold [ 16,34 ] and tungsten disulfi de (WS 2 ) 10-fold. [ 35 ] In the latter, plasmon-exciton coupling had been maximized. Quenching of PL from MoS 2 by p-type doping was reported to result from smaller MoS 2 electron affi nity than the Au work function. [ 36 ] Development of compact models that attribute plasmon-phonon coupling and hot electron transport to heterostructure composition, geometry, and arrangement has, to date, lagged experimental characterization.This work introduced use of the discrete dipole approximation (DDA) to Maxwell's equations to characterize excitation and damping of plasmon and exciton modes in near-fi eld maps and far-fi eld transmission UV-vis spectra of MoS 2 decorated with Au nanospheres (AuNS) and silver nanoprisms (AgNP). DDA simulations of heterostructures exhibited features corresponding to localized surface plasmon resonance (LSPR) and to A and B exciton transitions of the semiconductor, and exhibited modulation of these features by a silica substrate. MoS 2 -induced red-shifts of LSPR wavelengths were estimated within 2% of measured spectra. Near-fi eld energy maps at the nanoparticle-MoS 2 interface showed nanoparticle plasmon energy dissipated to the MoS 2 via plasmon damping and direct bandgap excitation. Linewidth analysis of plasmon damping was used to characterize energy transfer, including putative hot electron transfer, enabled by excitation above the ca. 0.9 eV Schottky barrier [ 37 ] for Au-MoS 2 interfaces. Results indicate DDA simulation could guide design of plasmon-exciton interactions in nanoparticle-decorated transition metal dichalcogenides (TMD) beyond MoS 2 , based on an available measured or simulated dielectric function. Results and Discussion Sample Characterization and MethodsAuNS (76 ± 13 nm diameter) and AgNP (53 ± 19 nm edge length) were drop-cast [ 38 ] onto monolayer MoS 2 -covered silica glass and characterized using a bright-fi eld optical microscope (Eclipse LV100; Nikon Instruments, Melville, NY, USA) with Energy and damping of resonances which occur in spectra of monolayer molybdenum disulfi de (MoS 2 ) decorated by noble metal nanospheres and prisms are examined by comparing discrete dipole approximation (DDA) simulations and transmission UV-vis measurements. Localized surface plasmon resonance (LSPR) as well as A and B exciton transitions of the semiconductor are characterized individually and in tandem on a silica substrate. Extinction energies for LSPR and direct bandgap transition of MoS 2 estimated by DDA are within 2% of measured values for gold nanospheres and silver nanoprisms. Resonant near-fi elds mapped at nanoparticle-MoS 2 interfaces show plasmon damping via energy dissipation to the MoS 2 and direct bandgap excitation. Linewidth ana...

Plasmon-Mediated Electron Injection from Au Nanorods into MoS2: Traditional versus Photoexcitation Mechanism

“…15,16 This challenge has motivated intense research efforts focusing on enhancing light absorption by metallic particle sensitization and the resulting exciton-plasmon interactions. [17][18][19][20][21] Excitation of many types of metal particles in the visible or ultraviolet (UV) frequency range stimulates collective motions of electrons, known as surface plasmons, that exhibit wave-like densities extending beyond the material surface. Such coherent oscillations of conduction band electrons induced by an electromagnetic field give rise to strong absorption and scattering resonances, 22 driving charge separation at metal-semiconductor interfaces.…”

“…The advantageous properties of localized plasmon resonances have motivated many recent experiments focusing on the fabrication and characterization of various semiconductors sensitized with plasmonic particles, and showing promising photovoltaic and photocatalytic properties. [16][17][18][19][20][21] Shi and co-workers demonstrated that monolayer MoS 2 sensitized with gold nano-antennas exhibits a significantly enhanced photoresponse at the wavelength of the localized surface plasmon resonance. 20 Chen and co-workers reported that plasmonic-MoS 2 hybrids dramatically…”

Production of monolayer-rich gold-decorated 2H–WS2 nanosheets by defect engineering

“…[25][26][27][28] As a result, Au 0 is produced and nucleates to form Au nanoparticles (AuNPs). Such TMD-Au hybrids are interesting for a number of applications ranging from rechargeable batteries, 27 to biosensing, 29,30 optoelectronics, [31][32][33] and catalysis. [34][35][36] Finally, as in any material, defects largely control the properties of the 2D nanosheets.…”

Localized plasmonic fields of nanoantennas enhance second harmonic generation from two-dimensional molybdenum disulfide

“…Examination of optoelectronic processes in nanoantenna-TMD heterostructures has to date focused on linear optical operations, where polarization, , responds linearly to the excitation field at frequency ω according to (1) . As examples, far-field optical absorption and scattering activity, 1 10-1000x enhanced TMD absorption/emission, 2 photoluminescence (PL) quenching, 3 and 11 to 38% efficient plasmonic hot electron transport 4,5 have been reported. Extraordinary second harmonic generation (SHG) and frequency mixing has been measured from twodimensional (2D) TMD arising from the second-order nonlinear contribution to that scales with 2 according to their large (2) .…”