Semiconductor Quantum Dot Lifetime Near an Atomically Smooth Ag Film Exhibits a Narrow Distribution

Abstract

We investigate photoluminescence from individual “giant” CdSe/CdS core/thick-shell quantum dots (gQDs) placed near an epitaxial Ag film with an atomically smooth surface. The key observation is that the lifetimes of the gQDs are drastically reduced and exhibit a remarkably narrow distribution compared to the gQDs deposited on a thermally deposited Ag film. The larger variations in gQDs’ lifetimes on the thermally deposited Ag film arise from excitonic coupling to localized surface plasmons associated with nanoscale surface corrugations of different heights. A calculation is performed based on a simple model system of a QD coupled to a metallic nanosphere. The calculation shows that the QD lifetime initially shortens and reaches a saturated value with increasing radius of the metal nanoparticle (MNP). Because the epitaxial film can be treated as a sphere with an infinitely large radius, the calculation confirms and explains the different QD dynamics near the two types of Ag films as observed experimentally. Our studies demonstrate that epitaxial Ag films serve as an ideal material platform for reliable control over the QD lifetime and may lead to improved photodetectors and light emitting devices requiring fast response or modulation.

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr3 anti-Stokes photoluminescence

“…In comparison with the control, the uniform Au nanoparticle coverage sample emits an additional 10.1 meV of thermal energy per up-converted photon. It is known that coupling fluorescent semiconductors to a metal decreases their fluorescent lifetime [20], and this has been additionally demonstrated for CsPbBr 3 with Au nanoparticles deposited on the perovskite surface [21]. One explanation of the blue-shift reported here may be that the reduction in the fluorescence lifetime prevents the energy transfer between particles that would result in red-shifted emission.…”

Quantum dot plasmonics: from weak to strong coupling

“…Indeed, ever since the emergence of this field there were multiple attempts to control and study the PL of individual QDs, rather than an ensemble of particles [80,[90][91][92][93][94][95][96][97][98][99][100][101][102][103][104]. Early on, Shimizu et al [90] studied the fluorescence behavior of single CdSe(ZnS) core-shell QDs interacting with a rough metal film.…”

Near‐Infrared, Heavy Metal‐Free Colloidal “Giant” Core/Shell Quantum Dots

“…For example, in InP/CdS g‐QDs, the wave functions of electrons and holes are spatially separated to form a fully type‐II band structure . Due to these features, g‐QD heterostructures such as CdSe/CdS g‐QDs/MoS 2 (drop casting g‐QDs on MoS 2 films grown by chemical vapor deposition) and CdSe/CdS g‐QDs/Ag (drop the g‐QD solution on Ag films prepared via molecular beam epitaxy) have recently emerged, showing promise for applications in energy technologies including photodetectors and LEDs …”