Surface plasmon inhibited photo-luminescence activation in CdSe/ZnS core–shell quantum dots

Abstract

In a composite film of Cd x Se y Zn1-x S1-y gradient core-shell quantum dots (QDs) and gold nanorods (NRs), the optical properties of the QDs are drastically affected by the plasmonic nanoparticles. We provide a careful study of the two-step formation of the film and its morphology. Subsequently we focus on QD luminescence photoactivation-a process induced by photochemical changes on the QD surface. We observe that even a sparse coverage of AuNRs can completely inhibit the photoactivation of the QDs' emission in the film. We demonstrate that the inhibition can be accounted for by a rapid energy transfer between QDs and AuNRs. Finally, we propose that the behavior of emission photoactivation can be used as a signature to distinguish between energy and electron transfer in the QD-based materials.

Photo-stability of CsPbBr3 perovskite quantum dots for optoelectronic application

“…A pulsed diode laser, triggered externally at 2.5 MHz, was used to excite the sample at 438 nm (at fluence of 0.5 μJ cm −2 ). The pulse duration of the laser was about 200 ps [16]. The emitted photons were detected with a 450 nm long band pass filter and focused onto a fast avalanche photodiode (SPAD, Micro Photon Device) with response time less than 50 ps.…”

Size- and Wavelength-Dependent Two-Photon Absorption Cross-Section of CsPbBr3 Perovskite Quantum Dots

“…The initially excited hot state will relax in subpicosecond time scale to the band edge. 21,31,49,50 Finally the electron−hole pairs recombine though radiative (photoluminescence emission) and nonradiative processes. 31 We used transient absorption spectroscopy to measure twophoton absorption cross-sections of CsPbBr 3 QDs of different sizes (4.6−11.4 nm).…”

“…We conclude that the TPA process in CsPbBr 3 QDs proceeds through a virtual level, and the final state is an exciton band state and not a defect state (Figure B). The initially excited hot state will relax in subpicosecond time scale to the band edge. ,,, Finally the electron–hole pairs recombine though radiative (photoluminescence emission) and nonradiative processes …”

Fluorescence sensing of amine vapours based on ZnS-supramolecular organogel hybrid films

“…Such a wide low-energy PL spectrum is mainly due to trapped state emissions originates from surface defect sites, which is related to excess sulfur, low crystallization and other interface defects of the nano-crystals. [48][49][50] In fact, band edge and trap emissions oen coexist in sulphide semiconductor nanoparticles, 51,52 and by increasing the number of surface defects, the trap emission could be strengthened signicantly. 52 Thus, the band edge emission obtained through the recombination mechanism could be completely inhibited.…”