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Shulenberger KE, Jilek MR, Sherman SJ, Hohman BT, Dukovic G. Electronic Structure and Excited State Dynamics of Cadmium Chalcogenide Nanorods. Chem Rev 2023; 123:3852-3903. [PMID: 36881852 DOI: 10.1021/acs.chemrev.2c00676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The cylindrical quasi-one-dimensional shape of colloidal semiconductor nanorods (NRs) gives them unique electronic structure and optical properties. In addition to the band gap tunability common to nanocrystals, NRs have polarized light absorption and emission and high molar absorptivities. NR-shaped heterostructures feature control of electron and hole locations as well as light emission energy and efficiency. We comprehensively review the electronic structure and optical properties of Cd-chalcogenide NRs and NR heterostructures (e.g., CdSe/CdS dot-in-rods, CdSe/ZnS rod-in-rods), which have been widely investigated over the last two decades due in part to promising optoelectronic applications. We start by describing methods for synthesizing these colloidal NRs. We then detail the electronic structure of single-component and heterostructure NRs and follow with a discussion of light absorption and emission in these materials. Next, we describe the excited state dynamics of these NRs, including carrier cooling, carrier and exciton migration, radiative and nonradiative recombination, multiexciton generation and dynamics, and processes that involve trapped carriers. Finally, we describe charge transfer from photoexcited NRs and connect the dynamics of these processes with light-driven chemistry. We end with an outlook that highlights some of the outstanding questions about the excited state properties of Cd-chalcogenide NRs.
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Affiliation(s)
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Benjamin T Hohman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States.,Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
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Thomas EM, Ghimire S, Kohara R, Anil AN, Yuyama KI, Takano Y, Thomas KG, Biju V. Blinking Suppression in Highly Excited CdSe/ZnS Quantum Dots by Electron Transfer under Large Positive Gibbs (Free) Energy Change. ACS NANO 2018; 12:9060-9069. [PMID: 30103604 DOI: 10.1021/acsnano.8b03010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconductor quantum dots with stable photoluminescence are necessary for next generation optoelectronic and photovoltaic devices. Photoluminescence intensity fluctuations of cadmium and lead chalcogenide quantum dots have been extensively investigated since the first observation of blinking in CdSe nanocrystals in 1996. In a quantum dot, blinking originates from stochastic photocharging, nonradiative Auger recombination, and delayed neutralization. So far, blinking is suppressed by defect passivation, electron transfer, and shell preparation, but without any deep insight into free energy change of electron transfer. We report real-time detection of significant blinking suppression for CdSe/ZnS quantum dots exposed to N, N-dimethylaniline, which is accompanied by a considerable increase in the time-averaged photoluminescence intensity of quantum dots. Although the Gibbs (free) energy change (Δ Get = +2.24 eV), which is estimated electrochemically and from density functional theory calculations, is unfavorable for electron transfer from N, N-dimethylaniline to a quantum dot in the minimally excited (band-edge) state, electron transfer is obvious when a quantum dot is highly excited. Nonetheless, Δ Get crosses from the positive to negative scale as the solvent dielectric constant exceeds 5, favoring electron transfer from N, N-dimethylaniline to a quantum dot excited to the band-edge state. Based on single-molecule photoluminescence and ensemble electron transfer studies, we assign blinking suppression to the transfer of an electron from N, N-dimethylaniline to the hot hole state of a quantum dot. In addition to blinking suppression by electron transfer, complete removal of blinking is limited by short-living OFF states induced by the negative trion.
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Affiliation(s)
- Elizabeth Mariam Thomas
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India
| | - Sushant Ghimire
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
| | - Reiko Kohara
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
| | - Ajith Nair Anil
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
| | - Ken-Ichi Yuyama
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
| | - Yuta Takano
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
| | - K George Thomas
- School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India
| | - Vasudevanpillai Biju
- Research Institute for Electronic Science , Hokkaido University , Sapporo , Hokkaido 001-0020 , Japan
- Graduate School of Environmental Science , Hokkaido University , Sapporo , Hokkaido 060-0810 , Japan
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Ko HC, Yuan CT, Tang J. Probing and controlling fluorescence blinking of single semiconductor nanoparticles. NANO REVIEWS 2011; 2:NANO-2-5895. [PMID: 22110871 PMCID: PMC3215194 DOI: 10.3402/nano.v2i0.5895] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 01/11/2011] [Accepted: 01/12/2011] [Indexed: 11/14/2022]
Abstract
In this review we present an overview of the experimental and theoretical development on fluorescence intermittency (blinking) and the roles of electron transfer in semiconductor crystalline nanoparticles. Blinking is a very interesting phenomenon commonly observed in single molecule/particle experiments. Under continuous laser illumination, the fluorescence time trace of these single nanoparticles exhibit random light and dark periods. Since its first observation in the mid-1990s, this intriguing phenomenon has attracted wide attention among researchers from many disciplines. We will first present the historical background of the discovery and the observation of unusual inverse power-law dependence for the waiting time distributions of light and dark periods. Then, we will describe our theoretical modeling efforts to elucidate the causes for the power-law behavior, to probe the roles of electron transfer in blinking, and eventually to control blinking and to achieve complete suppression of the blinking, which is an annoying feature in many applications of quantum dots as light sources and fluorescence labels for biomedical imaging.
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Affiliation(s)
- Hsien-Chen Ko
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
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Tang J, Lee DH, Yeh YC, Yuan CT. Short-time power-law blinking statistics of single quantum dots and a test of the diffusion-controlled electron transfer model. J Chem Phys 2009; 131:064506. [PMID: 19691396 DOI: 10.1063/1.3205406] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work we analyzed the blinking statistics data of single CdSe/ZnS quantum dots at very short times to test some predictions of the diffusion-controlled electron transfer (DCET) model. Using autocorrelation function (ACF) approach we could extract the exponent of the inverse power-law blinking statistics down to 1 micros. Such an approach also minimizes human subjectivity in choosing a bin time and an on-off threshold. We showed that the observed stretched exponential decay in the ACF and its relationship to the blinking statistics are consistent with the DCET model, and we set an upper bound for the characteristic time constant t(c).
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Affiliation(s)
- Jau Tang
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan 11529.
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Tang J. The effects of anomalous diffusion on power-law blinking statistics of CdSe nanorods. J Chem Phys 2009; 129:084709. [PMID: 19044843 DOI: 10.1063/1.2969073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this study of fluorescence blinking statistics for nanorods, we present a diffusion-controlled reaction model that leads to a more general formula: t(-m) exp[-(Gammat)(n)]. This formula describes a short-time power law with a crossover to a stretched exponential decay at later times. Based on quantum Brownian motion for a coupled central harmonic oscillator coupled to heat bath oscillators, we show that the position distribution follows anomalous diffusion with time-dependent diffusion coefficient and drift coefficient. The first and the second moments of the energy fluctuations are shown to be related to the exponent m and n for the blinking statistics.
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Affiliation(s)
- Jau Tang
- Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
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Wang S, Querner C, Fischbein MD, Willis L, Novikov DS, Crouch CH, Drndic M. Blinking statistics correlated with nanoparticle number. NANO LETTERS 2008; 8:4020-6. [PMID: 18844430 DOI: 10.1021/nl802696f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We report fluorescence of single semiconductor nanorods (NRs) and few-NR clusters, correlated with transmission electron microscopy for direct determination of the number of NRs present in a single fluorescent source. For samples drop-cast from dilute solutions, we show that the majority of the blinking sources (approximately 75%) are individual NRs while the remaining sources are small clusters consisting of up to 15 NRs. Clusters containing two or three NRs exhibit intermittent fluorescence intensity trajectories, I(t), similar to those of individual NRs. The associated statistical parameters of on- and off-time probability densities for two- and three-NR clusters are indistinguishable from those of individual NRs. In contrast, statistically distinguishable blinking parameters are observed for clusters of five or more particles. In particular, the "truncation time" of the on-time probability density, i.e., the time characterizing the transition from a power law to an exponential decay, was found to increase superlinearly with the number of particles. Our long (2.4 x 10(4) s) blinking measurements also directly reveal the previously unobserved truncation of the power law distribution of the off-times for single nanoparticles.
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Affiliation(s)
- Siying Wang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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