Fluorescence lifetime of Mn-doped ZnSe quantum dots with size dependence

Abstract

Radiative lifetimes of high quality Mn:ZnSe nanocrystals synthesized by nucleation-doping method are experimentally measured at wavelength near 580 nm. The slow decay rate in millisecond time scale is identified as the radiative decay from the 4 T 1 metastable excited state of Mn 2+ ions embedded in the ZnSe nanocrystals. Also, two fast decay components are measured at this wavelength with much lower intensities, which can be attributed to the emission tails from the host ZnSe nanocrystals and from the surface-trap states or the self-activated luminescence due to Mn ion pairs, respectively. Size dependences of the radiative decay rates for the Mn:ZnSe samples are measured.

Evolution of fluorescence resonance energy transfer between close-packed CdSeS quantum dots under two-photon excitation

“…One preferential solution to this challenge is to use doped/alloyed QDs [2], since their emission can be tuned by varying the doping composition when the size is fixed [3]. Also, dopants in QDs may introduce new characteristics such as the cubic power dependence luminescence and longer lifetime in Mn-doped QDs [4]. Thus, new materials and techniques for understanding the underlying physics of these processes are extremely valuable.…”

Optical properties of Cu ions‐doped ZnSe quantum dots in silicate glasses

“…Both surface passivation by forming core/shell structures and doping of transition‐metal ions are able to improve the photoluminescence quantum yield (PL QY) of QDs. Those doped transition‐metal ions such as Mn, Cu, Ag, Fe, Ni, and Co, create impurity energy levels in the forbidden energy gap of QDs and provide new recombination pathway for the photo‐generated electrons, thus reducing the nonradiative recombination of excitons mediated by the surface states and yielding photoluminescence with large Stokes shift, longer lifetimes and broader PL range . Nucleation‐doping and growth‐doping proposed by Peng et al greatly enhanced the PL QY of transition metal‐doped QDs, and photo‐oxidation of the transition‐metal dopants are successfully prevented by forming the core/shell structure …”

Impurity Location-Dependent Relaxation Dynamics of Cu:CdS Quantum Dots

“…Transition-metal or rare-earth ion-doped quantum dots (QDs), especially sulfides, are emerging as alternatives to semiconductor QDs with stable, strong, and tunable luminescence in the visible spectral region for different optoelectronic applications. Minimized self-absorption [3, 4], long excited-state lifetimes [5, 6], tunable emission spectral widths [7], and thermal stability [8, 9] are the characteristic properties of these nanocrystals making those doped nanocrystals as important QDs. Especially, semiconductor nanocrystals of a wide band-gap such as cadmium or zinc chalcogenides, doped with transition-metal ions, become alternative materials to overcome the limitation of organic phosphor-based LEDs (OLEDs) because QD-LEDs do not suffer from the spin statistics that limits the internal quantum efficiency of fluorescent OLEDs [10].…”