Multi-wavelength intermittent photoluminescence of single CdSe quantum dots

Abstract

A single chromophore detection using video-microscopy is one of the latest methodologies to reveal unique characteristics, which could not be obtained from ensemble measurements. Among many kinds of subjects, dynamic optical properties observed in colloidal semiconductor nanoparticles are attractive and important not only for the basis of photo-physics but also for application studies, e.g. biological labeling, electronic devices. In this study, fluorescence video-microscopy was performed on cadmium selenide (CdSe) quantum dots (QDs) spin-coated on a glass substrate. From single CdSe QDs detection, emissions at wavelengths separated over 60 nm were observed for the first time. This spectral feature was attributed to the existence of double-emissive relaxation processes in CdSe QDs. Photoluminescence intermittency was also observed both from relaxation processes. Fluorescence video-microscopy, which was advanced in biology, can be applicable for the real-time monitoring of dynamic properties in semiconductor photo-physics. q

Recent advances in synthesis and application of perovskite quantum dot based composites for photonics, electronics and sensors

“…Due to their quantum confinement effect that appears when the semiconductor materials' size is smaller than twice its Bohr radius, QDs process excitonic features and enhanced photoluminescence (PL) properties comparing to bulk materials [24][25][26]. Various types of QDs such as CdS [27], CdSe [13,15,28], ZnS [29], PbS [30], PbSe [31], SnS [32,33], SnSe [34] silicon [35] and halide perovskites have been explored and applied in various applications.…”

Addressable photocharging of single quantum dots assisted with atomic force microscopy probe

“…Such blinking occurs frequently in the organically capped dots, while inorganic capping reduces the ionization frequency and leads to longer on-period. 21 In conclusion, we described a method of addressable photocharging of individual CdSe QDs deposited on a conductive substrate ͑graphite͒ in ambient conditions. An AFM probe squeezed the TOPO coating of QDs during scanning, which substantially accelerated the tunneling of the photoexcited electron from the QD to either conductive substrate or AFM probe.…”