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Yuan G, Higginbotham HF, Han J, Yadav A, Kirkwood N, Mulvaney P, Bell TDM, Cole JH, Funston AM. Tuning the Photoluminescence Anisotropy of Semiconductor Nanocrystals. ACS NANO 2023; 17:19109-19120. [PMID: 37748102 DOI: 10.1021/acsnano.3c05214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Semiconductor nanocrystals are promising optoelectronic materials. Understanding their anisotropic photoluminescence is fundamental for developing quantum-dot-based devices such as light-emitting diodes, solar cells, and polarized single-photon sources. In this study, we experimentally and theoretically investigate the photoluminescence anisotropy of CdSe semiconductor nanocrystals with various shapes, including plates, rods, and spheres, with either wurtzite or zincblende structures. We use defocused wide-field microscopy to visualize the emission dipole orientation and find that spheres, rods, and plates exhibit the optical properties of 2D, 1D, and 2D emission dipoles, respectively. We rationalize the seemingly counterintuitive observation that despite having similar aspect ratios (width/length), rods and long nanoplatelets exhibit different defocused emission patterns by considering valence band structures calculated using multiband effective mass theory and the dielectric effect. The principles are extended to provide general relationships that can be used to tune the emission dipole orientation for different materials, crystalline structures, and shapes.
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Affiliation(s)
- Gangcheng Yuan
- ARC Centre of Excellence in Exciton Science, Monash University, Clayton, Victoria 3800, Australia
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | | | - Jiho Han
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anchal Yadav
- ARC Centre of Excellence in Exciton Science, Monash University, Clayton, Victoria 3800, Australia
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Nicholas Kirkwood
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Paul Mulvaney
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Toby D M Bell
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Jared H Cole
- ARC Centre of Excellence in Exciton Science and Chemical and Quantum Physics, School of Science, RMIT University, Melbourne, 3001, Australia
| | - Alison M Funston
- ARC Centre of Excellence in Exciton Science, Monash University, Clayton, Victoria 3800, Australia
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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2
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Jasrasaria D, Weinberg D, Philbin JP, Rabani E. Simulations of nonradiative processes in semiconductor nanocrystals. J Chem Phys 2022; 157:020901. [PMID: 35840368 DOI: 10.1063/5.0095897] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The description of carrier dynamics in spatially confined semiconductor nanocrystals (NCs), which have enhanced electron-hole and exciton-phonon interactions, is a great challenge for modern computational science. These NCs typically contain thousands of atoms and tens of thousands of valence electrons with discrete spectra at low excitation energies, similar to atoms and molecules, that converge to the continuum bulk limit at higher energies. Computational methods developed for molecules are limited to very small nanoclusters, and methods for bulk systems with periodic boundary conditions are not suitable due to the lack of translational symmetry in NCs. This perspective focuses on our recent efforts in developing a unified atomistic model based on the semiempirical pseudopotential approach, which is parameterized by first-principle calculations and validated against experimental measurements, to describe two of the main nonradiative relaxation processes of quantum confined excitons: exciton cooling and Auger recombination. We focus on the description of both electron-hole and exciton-phonon interactions in our approach and discuss the role of size, shape, and interfacing on the electronic properties and dynamics for II-VI and III-V semiconductor NCs.
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Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - John P Philbin
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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3
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Flores-Pacheco A, Sánchez-Zeferino R, Saavedra-Rodríguez G, Contreras-Rascón JI, Díaz-Reyes J, Álvarez-Ramos ME. Enhanced Stokes-shift and dispersibility in non-polar PMMA solvent of CdTe quantum dots by silica coating. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Pandya R, Steinmetz V, Puttisong Y, Dufour M, Chen WM, Chen RYS, Barisien T, Sharma A, Lakhwani G, Mitioglu A, Christianen PCM, Legrand L, Bernardot F, Testelin C, Chin AW, Ithurria S, Chamarro M, Rao A. Fine Structure and Spin Dynamics of Linearly Polarized Indirect Excitons in Two-Dimensional CdSe/CdTe Colloidal Heterostructures. ACS NANO 2019; 13:10140-10153. [PMID: 31490653 DOI: 10.1021/acsnano.9b03252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Heterostructured two-dimensional colloidal nanoplatelets are a class of material that has attracted great interest for optoelectronic applications due to their high photoluminescence yield, atomically tunable thickness, and ultralow lasing thresholds. Of particular interest are laterally heterostructured core-crown nanoplatelets with a type-II band alignment, where the in-plane spatial separation of carriers leads to indirect (or charge transfer) excitons with long lifetimes and bright, highly Stokes shifted emission. Despite this, little is known about the nature of the lowest energy exciton states responsible for emission in these materials. Here, using polarization-controlled, steady-state, and time-resolved photoluminescence measurements, at temperatures down to 1.6 K and magnetic fields up to 30 T, we study the exciton fine structure and spin dynamics of archetypal type-II CdSe/CdTe core-crown nanoplatelets. Complemented by theoretical modeling and zero-field quantum beat measurements, we find the bright-exciton fine structure consists of two linearly polarized states with a fine structure splitting ∼50 μeV and an indirect exciton Landé g-factor of 0.7. In addition, we show the exciton spin lifetime to be in the microsecond range with an unusual B-3 magnetic field dependence. The discovery of linearly polarized exciton states and emission highlights the potential for use of such materials in display and imaging applications without polarization filters. Furthermore, the small exciton fine structure splitting and a long spin lifetime are fundamental advantages when envisaging CdSe/CdTe nanoplatelets as elementary bricks for the next generation of quantum devices, particularly given their ease of fabrication.
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Affiliation(s)
- Raj Pandya
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
| | - Violette Steinmetz
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Yuttapoom Puttisong
- Functional Electronic Materials, Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Marion Dufour
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris , PSL Research University, CNRS , 10 rue Vauquelin , 75005 Paris , France
| | - Weimin M Chen
- Functional Electronic Materials, Department of Physics, Chemistry and Biology , Linköping University , 58183 Linköping , Sweden
| | - Richard Y S Chen
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
| | - Thierry Barisien
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Ashish Sharma
- ARC Centre of Excellence in Exciton Science, School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Girish Lakhwani
- ARC Centre of Excellence in Exciton Science, School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Anatolie Mitioglu
- High Field Magnet Laboratory (HFML - EMFL) , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Peter C M Christianen
- High Field Magnet Laboratory (HFML - EMFL) , Radboud University , 6525 ED Nijmegen , The Netherlands
| | - Laurent Legrand
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Frédérick Bernardot
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Christophe Testelin
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Alex W Chin
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris , PSL Research University, CNRS , 10 rue Vauquelin , 75005 Paris , France
| | - Maria Chamarro
- Sorbonne Université CNRS-UMR 7588, Institut des NanoSciences de Paris , INSP, 4 place Jussieu , F-75005 Paris , France
| | - Akshay Rao
- Cavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , CB3 0HE Cambridge , United Kingdom
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Nandan Y, Mehata MS. Wavefunction Engineering of Type-I/Type-II Excitons of CdSe/CdS Core-Shell Quantum Dots. Sci Rep 2019; 9:2. [PMID: 30626883 PMCID: PMC6327053 DOI: 10.1038/s41598-018-37676-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/13/2018] [Indexed: 11/10/2022] Open
Abstract
Nanostructured semiconductors have the unique shape/size-dependent band gap tunability, which has various applications. The quantum confinement effect allows controlling the spatial distribution of the charge carriers in the core-shell quantum dots (QDs). Upon increasing shell thickness (e.g., from 0.25-3.25 nm) of core-shell QDs, the radial distribution function (RDF) of hole shifts towards the shell suggesting the confinement region switched from Type-I to Type-II excitons. As a result, there is a jump in the transition energy towards the higher side (blue shift). However, an intermediate state appeared as pseudo Type II excitons, in which holes are co-localized in the shell as well core whereas electrons are confined in core only, resulting in a dual absorption band (excitation energy), carried out by the analysis of the overlap percentage using the Hartree-Fock method. The findings are a close approximation to the experimental evidences. Thus, the understanding of the motion of e-h in core-shell QDs is essential for photovoltaic, LEDs, etc.
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Affiliation(s)
- Yashaswi Nandan
- Laser-Spectroscopy Laboratory, Department of Applied Physics, Delhi Technological University, Bawana Road, Delhi, 110042, India
| | - Mohan Singh Mehata
- Laser-Spectroscopy Laboratory, Department of Applied Physics, Delhi Technological University, Bawana Road, Delhi, 110042, India.
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Chang JH, Park P, Jung H, Jeong BG, Hahm D, Nagamine G, Ko J, Cho J, Padilha LA, Lee DC, Lee C, Char K, Bae WK. Unraveling the Origin of Operational Instability of Quantum Dot Based Light-Emitting Diodes. ACS NANO 2018; 12:10231-10239. [PMID: 30347988 DOI: 10.1021/acsnano.8b03386] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We investigate the operational instability of quantum dot (QD)-based light-emitting diodes (QLEDs). Spectroscopic analysis on the QD emissive layer within devices in chorus with the optoelectronic and electrical characteristics of devices discloses that the device efficiency of QLEDs under operation is indeed deteriorated by two main mechanisms. The first is the luminance efficiency drop of the QD emissive layer in the running devices owing to the accumulation of excess electrons in the QDs, which escalates the possibility of nonradiative Auger recombination processes in the QDs. The other is the electron leakage toward hole transport layers (HTLs) that accompanies irreversible physical damage to the HTL by creating nonradiative recombination centers. These processes are distinguishable in terms of the time scale and the reversibility, but both stem from a single origin, the discrepancy between electron versus hole injection rates into QDs. Based on experimental and calculation results, we propose mechanistic models for the operation of QLEDs in individual quantum dot levels and their degradation during operation and offer rational guidelines that promise the realization of high-performance QLEDs with proven operational stability.
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Affiliation(s)
- Jun Hyuk Chang
- School of Chemical and Biological Engineering , Seoul National University , Seoul 08826 , Korea
| | - Philip Park
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States
| | - Heeyoung Jung
- School of Electrical and Computer Engineering, Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Korea
| | - Byeong Guk Jeong
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Korea
| | - Donghyo Hahm
- School of Chemical and Biological Engineering , Seoul National University , Seoul 08826 , Korea
| | - Gabriel Nagamine
- Instituto de Fisica "Gleb Wataghin" , Universidade Estadual de Campinas , UNICAMP, P.O. Box 6165, 13083-859 Campinas , São Paulo , Brazil
| | - Jongkuk Ko
- Department of Chemical and Biological Engineering , Korea University , Seoul 02841 , Korea
| | - Jinhan Cho
- Department of Chemical and Biological Engineering , Korea University , Seoul 02841 , Korea
| | - Lazaro A Padilha
- Instituto de Fisica "Gleb Wataghin" , Universidade Estadual de Campinas , UNICAMP, P.O. Box 6165, 13083-859 Campinas , São Paulo , Brazil
| | - Doh C Lee
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the NanoCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Korea
| | - Changhee Lee
- School of Electrical and Computer Engineering, Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Korea
| | - Kookheon Char
- School of Chemical and Biological Engineering , Seoul National University , Seoul 08826 , Korea
| | - Wan Ki Bae
- SKKU Advanced Institute of Nanotechnology (SAINT) , Sungkyunkwan University , Suwon-si , Gyeonggi-do 16419 , Korea
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7
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Di Stasio F, Imran M, Akkerman QA, Prato M, Manna L, Krahne R. Reversible Concentration-Dependent Photoluminescence Quenching and Change of Emission Color in CsPbBr 3 Nanowires and Nanoplatelets. J Phys Chem Lett 2017; 8:2725-2729. [PMID: 28581755 DOI: 10.1021/acs.jpclett.7b01305] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We discuss the photoluminescence (PL) of quantum-confined CsPbBr3 colloidal nanocrystals of two different shapes (nanowires and nanoplatelets) at different concentrations in solution and in solid-state films. Upon increasing the nanocrystal concentration in solution, a constant drop in photoluminescence quantum yield is observed, accompanied by a significant PL red shift. This effect is reversible, and the original PL can be restored by diluting to the original concentration. We show that this effect can be in part attributed to self-absorption and partly to aggregation. In particular, for nanoplatelets, where the aggregation is mostly irreversible, while the self-absorption effect is reversible, the two contributions can be well separated. Finally, when dry solid-state films are prepared, the emission band is shifted into the green spectral region, close to the bulk CsPbBr3 band gap, thus preventing blue emission from such films.
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Affiliation(s)
- Francesco Di Stasio
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
| | - Muhammad Imran
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso, 31, 16146 Genova, Italy
| | - Quinten A Akkerman
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso, 31, 16146 Genova, Italy
| | - Mirko Prato
- Materials Characterization Facility, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
| | - Liberato Manna
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
| | - Roman Krahne
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy
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