Open AccessJournal Article
Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots
Christophe Galland,Yagnaseni Ghosh,Andrea Steinbrueck,Milan Sykora,Jennifer A. Hollingsworth,Victor I. Klimov,Han Htoon +6 more
TLDR
It is found that two distinct types of blinking are possible: conventional (A-type) blinking due to charging and discharging of the nanocrystal core, in which lower photoluminescence intensities correlate with shorter photolumscence lifetimes; and a second sort (B-type), in which large changes in the emission intensity are not accompanied by significant changes in emission dynamics.Abstract:
Photoluminescence blinking—random switching between states of high (ON) and low (OFF) emissivities—is a universal property of molecular emitters found in dyes, polymers, biological molecules and artificial nanostructures such as nanocrystal quantum dots, carbon nanotubes and nanowires. For the past 15 years, colloidal nanocrystals have been used as a model system to study this phenomenon. The occurrence of OFF periods in nanocrystal emission has been commonly attributed to the presence of an additional charge, which leads to photoluminescence quenching by non-radiative recombination (the Auger mechanism). However, this ‘charging’ model was recently challenged in several reports. Here we report time-resolved photoluminescence studies of individual nanocrystal quantum dots performed while electrochemically controlling the degree of their charging, with the goal of clarifying the role of charging in blinking. We find that two distinct types of blinking are possible: conventional (A-type) blinking due to charging and discharging of the nanocrystal core, in which lower photoluminescence intensities correlate with shorter photoluminescence lifetimes; and a second sort (B-type), in which large changes in the emission intensity are not accompanied by significant changes in emission dynamics. We attribute B-type blinking to charge fluctuations in the electron-accepting surface sites. When unoccupied, these sites intercept ‘hot’ electrons before they relax into emitting core states. Both blinking mechanisms can be electrochemically controlled and completely suppressed by application of an appropriate potential.read more
Citations
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Journal ArticleDOI
Hybrid passivated colloidal quantum dot solids
Alexander H. Ip,Susanna M. Thon,Sjoerd Hoogland,Oleksandr Voznyy,David Zhitomirsky,Ratan Debnath,Larissa Levina,Lisa R. Rollny,Graham H. Carey,Armin Fischer,Kyle W. Kemp,Illan J. Kramer,Zhijun Ning,André J. Labelle,Kang Wei Chou,Aram Amassian,Edward H. Sargent +16 more
TL;DR: The density of midgap trap states in CQD solids is quantified and shown to be limited by electron-hole recombination due to these states, and a robust hybrid passivation scheme is developed that can passivate trap sites that are inaccessible to much larger organic ligands.
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Organic Optoelectronic Materials: Mechanisms and Applications
TL;DR: The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials and highlights the capabilities of various experimental techniques for characterization, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field.
Journal ArticleDOI
Spectroscopic and Device Aspects of Nanocrystal Quantum Dots
Jeffrey M. Pietryga,Young-Shin Park,Young-Shin Park,Jaehoon Lim,Andrew F. Fidler,Wan Ki Bae,Sergio Brovelli,Victor I. Klimov +7 more
TL;DR: Recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion are examined.
Journal ArticleDOI
Bright triplet excitons in caesium lead halide perovskites
Michael Becker,Michael Becker,Roman Vaxenburg,Georgian Nedelcu,Georgian Nedelcu,Peter C. Sercel,Andrew Shabaev,Michael J. Mehl,John G. Michopoulos,Samuel G. Lambrakos,Noam Bernstein,John L. Lyons,Thilo Stöferle,Rainer F. Mahrt,Maksym V. Kovalenko,Maksym V. Kovalenko,David J. Norris,Gabriele Rainò,Gabriele Rainò,Alexander L. Efros +19 more
TL;DR: In this article, it was shown that the lowest exciton in caesium lead halide perovskites (CsPbX_3, with X = Cl, Br or I) involves a highly emissive triplet state.
Journal ArticleDOI
Controlling the influence of Auger recombination on the performance of quantum-dot light-emitting diodes
Wan Ki Bae,Young-Shin Park,Jaehoon Lim,Donggu Lee,Lazaro A. Padilha,Lazaro A. Padilha,Hunter McDaniel,Istvan Robel,Changhee Lee,Jeffrey M. Pietryga,Victor I. Klimov +10 more
TL;DR: This work finds that because of significant charging of quantum dots with extra electrons, Auger recombination greatly impacts both LED efficiency and the onset of efficiency roll-off at high currents, and demonstrates two specific approaches using heterostructured quantum dots.
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Journal Article
Fluorescence intermittency in single cadmium selenide nanocrystals
M. Nirmal,B. O. Dabbousi,Moungi G. Bawendi,John J. Macklin,J. K. Trautman,Timothy D. Harris,Louis E. Brus +6 more
TL;DR: In this article, it was shown that light emission from single fluorescing nanocrystals of cadmium selenide under continuous excitation turns on and off intermittently with a characteristic timescale of about 0.5 seconds.
Journal ArticleDOI
Quantization of multiparticle auger rates in semiconductor quantum dots
Victor I. Klimov,Alexander Mikhailovsky,Duncan W. McBranch,C. A. Leatherdale,Moungi G. Bawendi +4 more
TL;DR: It is observed that in the quantum-confined regime, the Auger constant is strongly size-dependent and decreases with decreasing the quantum dot size as the radius cubed.