1
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Gunnarsson WB, Roh K, Zhao L, Murphy JP, Grede AJ, Giebink NC, Rand BP. Toward Nonepitaxial Laser Diodes. Chem Rev 2023. [PMID: 37219995 DOI: 10.1021/acs.chemrev.2c00721] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Thin-film organic, colloidal quantum dot, and metal halide perovskite semiconductors are all being pursued in the quest for a wavelength-tunable diode laser technology that does not require epitaxial growth on a traditional semiconductor substrate. Despite promising demonstrations of efficient light-emitting diodes and low-threshold optically pumped lasing in each case, there are still fundamental and practical barriers that must be overcome to reliably achieve injection lasing. This review outlines the historical development and recent advances of each material system on the path to a diode laser. Common challenges in resonator design, electrical injection, and heat dissipation are highlighted, as well as the different optical gain physics that make each system unique. The evidence to date suggests that continued progress for organic and colloidal quantum dot laser diodes will likely hinge on the development of new materials or indirect pumping schemes, while improvements in device architecture and film processing are most critical for perovskite lasers. In all cases, systematic progress will require methods that can quantify how close new devices get with respect to their electrical lasing thresholds. We conclude by discussing the current status of nonepitaxial laser diodes in the historical context of their epitaxial counterparts, which suggests that there is reason to be optimistic for the future.
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Affiliation(s)
- William B Gunnarsson
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Kwangdong Roh
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Lianfeng Zhao
- Holcombe Department of Electrical and Computer Engineering, Clemson University, Clemson, South Carolina 29634, United States
| | - John P Murphy
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Alex J Grede
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Noel C Giebink
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Barry P Rand
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States
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2
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Durmusoglu EG, Hu S, Hernandez-Martinez PL, Izmir M, Shabani F, Guo M, Gao H, Isik F, Delikanli S, Sharma VK, Liu B, Demir HV. High External Quantum Efficiency Light-Emitting Diodes Enabled by Advanced Heterostructures of Type-II Nanoplatelets. ACS NANO 2023; 17:7636-7644. [PMID: 36912794 PMCID: PMC10134493 DOI: 10.1021/acsnano.3c00046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
Colloidal quantum wells (CQWs), also known as nanoplatelets (NPLs), are exciting material systems for numerous photonic applications, including lasers and light-emitting diodes (LEDs). Although many successful type-I NPL-LEDs with high device performance have been demonstrated, type-II NPLs are not fully exploited for LED applications, even with alloyed type-II NPLs with enhanced optical properties. Here, we present the development of CdSe/CdTe/CdSe core/crown/crown (multi-crowned) type-II NPLs and systematic investigation of their optical properties, including their comparison with the traditional core/crown counterparts. Unlike traditional type-II NPLs such as CdSe/CdTe, CdTe/CdSe, and CdSe/CdSexTe1-x core/crown heterostructures, here the proposed advanced heterostructure reaps the benefits of having two type-II transition channels, resulting in a high quantum yield (QY) of 83% and a long fluorescence lifetime of 73.3 ns. These type-II transitions were confirmed experimentally by optical measurements and theoretically using electron and hole wave function modeling. Computational study shows that the multi-crowned NPLs provide a better-distributed hole wave function along the CdTe crown, while the electron wave function is delocalized in the CdSe core and CdSe crown layers. As a proof-of-concept demonstration, NPL-LEDs based on these multi-crowned NPLs were designed and fabricated with a record high external quantum efficiency (EQE) of 7.83% among type-II NPL-LEDs. These findings are expected to induce advanced designs of NPL heterostructures to reach a fascinating level of performance, especially in LEDs and lasers.
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Affiliation(s)
- Emek G. Durmusoglu
- LUMINOUS!
Centre of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering,
School of Physical and Mathematical Sciences, School of Materials
Science and Engineering, Nanyang Technological
University, Singapore 639798
| | - Sujuan Hu
- State
Key Laboratory of Optoelectronic Materials and Technologies, School
of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Pedro Ludwig Hernandez-Martinez
- LUMINOUS!
Centre of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering,
School of Physical and Mathematical Sciences, School of Materials
Science and Engineering, Nanyang Technological
University, Singapore 639798
| | - Merve Izmir
- LUMINOUS!
Centre of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering,
School of Physical and Mathematical Sciences, School of Materials
Science and Engineering, Nanyang Technological
University, Singapore 639798
| | - Farzan Shabani
- Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM—Institute of Materials Science and Nanotechnology and
National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
| | - Min Guo
- State
Key Laboratory of Optoelectronic Materials and Technologies, School
of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Huayu Gao
- State
Key Laboratory of Optoelectronic Materials and Technologies, School
of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Furkan Isik
- Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM—Institute of Materials Science and Nanotechnology and
National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
| | - Savas Delikanli
- Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM—Institute of Materials Science and Nanotechnology and
National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
| | - Vijay Kumar Sharma
- LUMINOUS!
Centre of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering,
School of Physical and Mathematical Sciences, School of Materials
Science and Engineering, Nanyang Technological
University, Singapore 639798
| | - Baiquan Liu
- State
Key Laboratory of Optoelectronic Materials and Technologies, School
of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Hilmi Volkan Demir
- LUMINOUS!
Centre of Excellence for Semiconductor Lighting and Displays, The
Photonics Institute, School of Electrical and Electronic Engineering,
School of Physical and Mathematical Sciences, School of Materials
Science and Engineering, Nanyang Technological
University, Singapore 639798
- Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM—Institute of Materials Science and Nanotechnology and
National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey
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3
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Zhang M, Bi C, Xia Y, Sun X, Wang X, Liu A, Tian S, Liu X, de Leeuw NH, Tian J. Water-Driven Synthesis of Deep-Blue Perovskite Colloidal Quantum Wells for Electroluminescent Devices. Angew Chem Int Ed Engl 2023; 62:e202300149. [PMID: 36692366 DOI: 10.1002/anie.202300149] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 01/25/2023]
Abstract
Perovskite colloidal quantum wells (QWs) are promising to realize narrow deep-blue emission, but the poor optical performance and stability suppress their practical application. Here, we creatively propose a water-driven synthesis strategy to obtain size-homogenized and strongly confined deep-blue CsPbBr3 QWs, corresponding to three monolayers, which emit at the deep-blue wavelength of 456 nm. The water controls the orientation and distribution of the ligands on the surface of the nanocrystals, thus inducing orientated growth through the Ostwald ripening process by phagocytizing unstable nanocrystals to form well-crystallized QWs. These QWs present remarkable stability and high photoluminescence quantum yield of 94 %. Furthermore, we have prepared light-emitting diodes based on the QWs via the all-solution fabrication strategy, achieving an external quantum efficiency of 1 % and luminance of 2946 cd m-2 , demonstrating state-of-the-art brightness for perovskite QW-based LEDs.
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Affiliation(s)
- Mengqi Zhang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.,Shunde Innovation School, University of Science and Technology Beijing, Foshan, Guangdong, 528399, China
| | - Chenghao Bi
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.,Shunde Innovation School, University of Science and Technology Beijing, Foshan, Guangdong, 528399, China
| | - Yuexing Xia
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, Beijing National Center for Nanoscience and Technology, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xuejiao Sun
- Institute of Semiconductors Chinese Academy of Sciences, Beijing, 100083, China
| | - Xingyu Wang
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Aqiang Liu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.,Shunde Innovation School, University of Science and Technology Beijing, Foshan, Guangdong, 528399, China
| | - Shuyu Tian
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.,Shunde Innovation School, University of Science and Technology Beijing, Foshan, Guangdong, 528399, China
| | - Xinfeng Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, Beijing National Center for Nanoscience and Technology, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Nora H de Leeuw
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Jianjun Tian
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.,Shunde Innovation School, University of Science and Technology Beijing, Foshan, Guangdong, 528399, China
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4
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Failla M, García Flórez F, Salzmann BBV, Vanmaekelbergh D, Stoof HTC, Siebbeles LDA. Effects of Pump Photon Energy on Generation and Ultrafast Relaxation of Excitons and Charge Carriers in CdSe Nanoplatelets. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:1899-1907. [PMID: 36761230 PMCID: PMC9900632 DOI: 10.1021/acs.jpcc.2c07292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/21/2022] [Indexed: 06/18/2023]
Abstract
We studied the initial nature and relaxation of photoexcited electronic states in CdSe nanoplatelets (NPLs). Ultrafast transient optical absorption (TA) measurements were combined with the theoretical analysis of the formation and decay of excitons, biexcitons, free charge carriers, and trions. In the latter, photons and excitons were treated as bosons and free charge carriers as fermions. The initial quantum yields of heavy-hole (HH) excitons, light-hole (LH) excitons, and charge carriers vary strongly with photon energy, while thermal relaxation occurs always within 1 ps. After that, the population of LH excitons is negligible due to relaxation to HH excitons or decay into free electrons and holes. Up to the highest average number of about four absorbed photons per NPL in our experiments, we found no signatures of the presence of biexcitons or larger complexes. Biexcitons were only observed due to the interaction of a probe-generated exciton with an exciton produced previously by the pump pulse. For higher pump photon energies, the initial presence of more free charge carriers leads to formation of trions by probe photons. On increasing the number of absorbed pump photons in an NPL, the yield of excitons becomes higher as compared to free charge carriers, since electron-hole recombination becomes more likely. In addition to a TA absorption feature at energy below the HH exciton peak, we also observed a TA signal at the high-energy side of this peak, which we attribute to formation of LH-HH biexcitons or trions consisting of a charge and LH exciton.
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Affiliation(s)
- Michele Failla
- Chemical
Engineering Department, Delft University
of Technology, Van der Maasweg 9, 2629 HZDelft, The Netherlands
| | - Fransisco García Flórez
- Institute
for Theoretical Physics and Center for Extreme Matter and Emergent
Phenomena, Utrecht University, Princetonplein 5, 3584 CCUtrecht, The Netherlands
| | - Bastiaan B. V. Salzmann
- Condensed
Matter and Interfaces, Debye Institute, Utrecht University, Princetonplein 1, 3584 CCUtrecht, The Netherlands
| | - Daniel Vanmaekelbergh
- Condensed
Matter and Interfaces, Debye Institute, Utrecht University, Princetonplein 1, 3584 CCUtrecht, The Netherlands
| | - Henk T. C. Stoof
- Institute
for Theoretical Physics and Center for Extreme Matter and Emergent
Phenomena, Utrecht University, Princetonplein 5, 3584 CCUtrecht, The Netherlands
| | - Laurens D. A. Siebbeles
- Chemical
Engineering Department, Delft University
of Technology, Van der Maasweg 9, 2629 HZDelft, The Netherlands
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5
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Diroll BT, Guzelturk B, Po H, Dabard C, Fu N, Makke L, Lhuillier E, Ithurria S. 2D II-VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration. Chem Rev 2023; 123:3543-3624. [PMID: 36724544 DOI: 10.1021/acs.chemrev.2c00436] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II-VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II-VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II-VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron-hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Burak Guzelturk
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Hong Po
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Corentin Dabard
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Ningyuan Fu
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Lina Makke
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
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6
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Geuchies JJ, Dijkhuizen R, Koel M, Grimaldi G, du Fossé I, Evers WH, Hens Z, Houtepen AJ. Zero-Threshold Optical Gain in Electrochemically Doped Nanoplatelets and the Physics Behind It. ACS NANO 2022; 16:18777-18788. [PMID: 36256901 PMCID: PMC9706803 DOI: 10.1021/acsnano.2c07519] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/13/2022] [Indexed: 06/07/2023]
Abstract
Colloidal nanoplatelets (NPLs) are promising materials for lasing applications. The properties are usually discussed in the framework of 2D materials, where strong excitonic effects dominate the optical properties near the band edge. At the same time, NPLs have finite lateral dimensions such that NPLs are not true extended 2D structures. Here we study the photophysics and gain properties of CdSe/CdS/ZnS core-shell-shell NPLs upon electrochemical n doping and optical excitation. Steady-state absorption and PL spectroscopy show that excitonic effects are weaker in core-shell-shell nanoplatelets due to the decreased exciton binding energy. Transient absorption studies reveal a gain threshold of only one excitation per nanoplatelet. Using electrochemical n doping, we observe the complete bleaching of the band edge exciton transitions. Combining electrochemical doping with transient absorption spectroscopy, we demonstrate that the gain threshold is fully removed over a broad spectral range and gain coefficients of several thousand cm-1 are obtained. These doped NPLs are the best performing colloidal nanomaterial gain medium reported to date, with the lowest gain threshold and broadest gain spectrum and gain coefficients that are 4 times higher than in n-doped colloidal quantum dots. The low exciton binding energy due to the CdS and ZnS shells, in combination with the relatively small lateral size of the NPLs, results in excited states that are effectively delocalized over the entire platelet. Core-shell NPLs are thus on the border between strong confinement in QDs and dominant Coulombic effects in 2D materials. We demonstrate that this limit is in effect ideal for optical gain and that it results in an optimal lateral size of the platelets where the gain threshold per nm2 is minimal.
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Affiliation(s)
- Jaco J. Geuchies
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Robbert Dijkhuizen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Marijn Koel
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Gianluca Grimaldi
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Indy du Fossé
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Wiel H. Evers
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Zeger Hens
- Department
of Chemistry and Center for Nano and Biophotonics, Ghent University, 9000Ghent, Belgium
| | - Arjan J. Houtepen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
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7
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Shabani F, Dehghanpour Baruj H, Yurdakul I, Delikanli S, Gheshlaghi N, Isik F, Liu B, Altintas Y, Canımkurbey B, Demir HV. Deep-Red-Emitting Colloidal Quantum Well Light-Emitting Diodes Enabled through a Complex Design of Core/Crown/Double Shell Heterostructure. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106115. [PMID: 34894078 DOI: 10.1002/smll.202106115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/13/2021] [Indexed: 06/14/2023]
Abstract
Extending the emission peak wavelength of quasi-2D colloidal quantum wells has been an important quest to fully exploit the potential of these materials, which has not been possible due to the complications arising from the partial dissolution and recrystallization during growth to date. Here, the synthetic pathway of (CdSe/CdS)@(1-4 CdS/CdZnS) (core/crown)@(colloidal atomic layer deposition shell/hot injection shell) hetero-nanoplatelets (NPLs) using multiple techniques, which together enable highly efficient emission beyond 700 nm in the deep-red region, is proposed and demonstrated. Given the challenges of using conventional hot injection procedure, a method that allows to obtain sufficiently thick and passivated NPLs as the seeds is developed. Consequently, through the final hot injection shell coating, thick NPLs with superior optical properties including a high photoluminescence quantum yield of 88% are achieved. These NPLs emitting at 701 nm exhibit a full-width-at-half-maximum of 26 nm, enabled by the successfully maintained quasi-2D shape and minimum defects of the resulting heterostructure. The deep-red light-emitting diode (LED) device fabricated with these NPLs has shown to yield a high external quantum efficiency of 6.8% at 701 nm, which is on par with other types of LEDs in this spectral range.
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Affiliation(s)
- Farzan Shabani
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Hamed Dehghanpour Baruj
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Iklim Yurdakul
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Savas Delikanli
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Negar Gheshlaghi
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Furkan Isik
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Baiquan Liu
- School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yemliha Altintas
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Department of Materials Science and Nanotechnology, Abdullah Gül University, Kayseri, TR-38080, Turkey
| | - Betül Canımkurbey
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Central Research Laboratory, Amasya University, Amasya, 05100, Turkey
| | - Hilmi Volkan Demir
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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8
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Wang L, Xiang D, Gao K, Wang J, Wu K. Colloidal n-Doped CdSe and CdSe/ZnS Nanoplatelets. J Phys Chem Lett 2021; 12:11259-11266. [PMID: 34766755 DOI: 10.1021/acs.jpclett.1c02856] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) are chemical versions of well-studied quantum wells (QWs). For QWs, gating and carrier doping are standard tools to manipulate their optical, electric, or magnetic properties. It would be highly desirable to use pure chemical methods to dope extra charge carriers into free-standing colloidal NPLs to achieve a similar level of manipulation. Here we report colloidal n-doped CdSe and CdSe/ZnS NPLs achieved through a photochemical doping method. The extra electrons doped into the conduction band edges are evidenced by exciton absorption bleaches recoverable through dedoping and the appearance of new intersub-band transitions in the near-infrared. A high surface ligand coverage is the key to successful doping; otherwise, the doped electrons can be depleted likely by unpassivated surface cations. Large trion binding energies of 20-30 meV are found for the n-doped CdSe NPLs, which, in contrast, are reduced by 1 order of magnitude in CdSe/ZnS core/shell NPLs due to dielectric screening. Furthermore, we identify a long-lived negative trion with a lifetime of 1.5-1.6 ns that is likely dominated by radiative recombination.
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Affiliation(s)
- Lifeng Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongmei Xiang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
| | - Kaimin Gao
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junhui Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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9
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Li Q, He S, Lian T. How Exciton and Single Carriers Block the Excitonic Transition in Two-Dimensional Cadmium Chalcogenide Nanoplatelets. NANO LETTERS 2020; 20:6162-6169. [PMID: 32697589 DOI: 10.1021/acs.nanolett.0c02461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cadmium chalcogenide nanoplatelets (NPLs) possess unique properties and have shown great potential in lasing, light-emitting diodes, and photocatalytic applications. However, the exact natures of the band-edge exciton and single carrier (electron and hole) states remain unclear, even though they affect the key properties and applications of these materials. Herein, we study the contribution of a single carrier (electron or hole) state to phase space filling of single exciton states of cadmium chalcogenide NPLs. With pump fluence dependent TA study and selective electron removal, we determine that a single electron and hole states contribute 85% and 12%, respectively, to the blocking of the excitonic transition in CdSe/ZnS core/shell NPLs. These observations can be rationalized by a model of band-edge exciton and single carrier states of 2D NPLs that differs significantly from that of quantum dots.
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Affiliation(s)
- Qiuyang Li
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| | - Sheng He
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
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Sanderson WM, Wang F, Schrier J, Buhro WE, Loomis RA. Intraband Relaxation Dynamics of Charge Carriers within CdTe Quantum Wires. J Phys Chem Lett 2020; 11:4901-4910. [PMID: 32491860 DOI: 10.1021/acs.jpclett.0c01326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The state-to-state intraband relaxation dynamics of charge carriers photogenerated within CdTe quantum wires (QWs) are characterized via transient absorption spectroscopy. Overlapping signals from the energetic-shifting of the quantum-confinement features and the occupancy of carriers in the states associated with these features are separated using the quantum-state renormalization model. Holes generated with an excitation energy of 2.75 eV reach the band edge within the instrument response of the measurement, ∼200 fs. This extremely short relaxation time is consistent with the low photoluminescence quantum yield of the QWs, ∼0.2%, and the presence of alternative relaxation pathways for the holes. The electrons relax through the different energetically available quantum-confinement states, likely via phonon coupling, with an overall rate of ∼0.6 eV ps-1.
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Affiliation(s)
- William M Sanderson
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Fudong Wang
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Joshua Schrier
- Department of Chemistry, Fordham University, The Bronx, New York 10458, United States
| | - William E Buhro
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Richard A Loomis
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
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Li Q, Lian T. Exciton Spatial Coherence and Optical Gain in Colloidal Two-Dimensional Cadmium Chalcogenide Nanoplatelets. Acc Chem Res 2019; 52:2684-2693. [PMID: 31433164 DOI: 10.1021/acs.accounts.9b00252] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Two-dimensional (2D) cadmium chalcogenide (CdX, X = Se, S, Te) colloidal nanoplatelets (NPLs) make up an emerging class of quantum well materials that exhibit many unique properties including uniform quantum confinement, narrow thickness distribution, large exciton binding energy, giant oscillator strength, long Auger lifetime, and high photoluminescence quantum yield. These properties have led to their great performances in optoelectrical applications such as lasing materials with a low threshold and large gain coefficient. Many of these properties are determined by the structure and dynamics of band-edge excitons in these 2D materials. Motivated by fundamental understanding of both 2D nanomaterials and their applications, the properties of 2D excitons have received intense recent interest. This Account provides an overview of three key properties of 2D excitons: how big is the 2D exciton (i.e., exciton center-of-mass coherent area); how the exciton moves in 2D NPLs (i.e., exciton in-plane transport mechanism); how multiple excitons interact with each other (i.e., biexciton Auger recombination); and their effects on the optical gain mechanism and threshold of colloidal NPLs. After a brief introduction in Section 1, the current understandings of 2D electronic structures of cadmium chalcogenide NPLs, and type-I CdSe/CdS and type-II CdSe/CdTe core/crown NPL heterostructures are summarized in Section 2. Section 3 discusses the direct measurement of exciton center-of-mass coherent area in 2D CdSe NPLs, its dependence on NPL parameters (thickness, lateral area, dielectric environment, and temperature), and the resulting giant oscillator strength transition (GOST) effect in 2D NPLs. 2D exciton diffusive in-plane transport in CdX NPLs and the comparison of exciton transport mechanisms in 2D NPLs and 1D nanorods are reviewed in Section 4. How Auger recombination lifetime depends on nanocrystal dimensions in NPLs, quantum dots, and nanorods is discussed in Section 5. The lateral area and thickness dependent Auger recombination rates of NPLs are shown to be well described by a model that accounts for the different dependence of the Auger recombination rates on the quantum confined and nonconfined dimensions. It is shown that Auger recombination rates do not follow the "universal volume scaling" law in 1D and 2D nanocrystals. Section 6 describes optical gain mechanisms in CdSe NPLs and the dependence of optical gain threshold on NPL lateral size, optical density, and temperature. The differences of optical gain properties in 0D-2D and the bulk materials are also discussed, highlighting the unique gain properties of 2D NPLs. At last, the Account ends with a summary and perspective of key remaining challenges in this field in Section 7.
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Affiliation(s)
- Qiuyang Li
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
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Geiregat P, Tomar R, Chen K, Singh S, Hodgkiss JM, Hens Z. Thermodynamic Equilibrium between Excitons and Excitonic Molecules Dictates Optical Gain in Colloidal CdSe Quantum Wells. J Phys Chem Lett 2019; 10:3637-3644. [PMID: 31187998 DOI: 10.1021/acs.jpclett.9b01607] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We show that optical gain in 2D CdSe colloidal quantum wells (CQWs) shows little saturation and coexists with exciton absorption over a broad range of excitation densities, in stark contrast with 0D CdSe colloidal quantum dots (CQDs). In addition, we demonstrate that photoexcited CQWs can absorb or emit light through the thermodynamically driven formation or radiative recombination of singlet excitonic molecules. Invoking stimulated emission through the molecule-exciton transition, we can quantify all of the remarkable gain characteristics of CQWs using only experimentally determined parameters, an advance that highlights a fundamental difference between multiexcitons in CQWs and CQDs. While strong confinement prohibits the dissociation of multiexcitons into separate excitons in 0D CQDs, excitons and excitonic molecules coexist in a 2D CQW at room temperature, with densities governed by an association/dissociation equilibrium, not by state-filling. Our finding points out future directions to optimize stimulated emission by excitonic 2D materials in general.
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Affiliation(s)
- Pieter Geiregat
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Renu Tomar
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Kai Chen
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6012 , New Zealand
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6012 , New Zealand
- The Dodd-Walls Centre for Photonic and Quantum Technologies , Dunedin 9054 , New Zealand
| | - Shalini Singh
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Justin M Hodgkiss
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6012 , New Zealand
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6012 , New Zealand
- The Dodd-Walls Centre for Photonic and Quantum Technologies , Dunedin 9054 , New Zealand
| | - Zeger Hens
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
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Li Q, Liu Q, Schaller RD, Lian T. Reducing the Optical Gain Threshold in Two-Dimensional CdSe Nanoplatelets by the Giant Oscillator Strength Transition Effect. J Phys Chem Lett 2019; 10:1624-1632. [PMID: 30892896 DOI: 10.1021/acs.jpclett.9b00759] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Two-dimensional CdSe nanoplatelets are promising lasing materials. Their large lateral areas reduce the optical gain threshold by increasing the oscillator strength and multiexciton lifetimes but also increase the gain threshold by requiring multiple band-edge excitons (>2) to reach the optical gain. We observe that the optical gain threshold of CdSe nanoplatelets at 4 K is ∼4-fold lower than that at room temperature. Transient absorption spectroscopy measurements indicate that the exciton center-of-mass coherent area is smaller than the lateral size at room temperature and extends to nearly the whole nanoplatelets at 4 K. This suggests that the reduction in the optical gain threshold at a low temperature can be attributed to exciton coherent area extension that reduces the saturation number of band-edge excitons to enable biexciton gain and increases the radiative decay rate, consistent with the giant oscillator strength transition effect. This work demonstrates a new direction for lowering the optical gain threshold of nanomaterials.
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Affiliation(s)
- Qiuyang Li
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , United States
| | - Qiliang Liu
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , United States
| | - Richard D Schaller
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Tianquan Lian
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , United States
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Guzelturk B, Pelton M, Olutas M, Demir HV. Giant Modal Gain Coefficients in Colloidal II-VI Nanoplatelets. NANO LETTERS 2019; 19:277-282. [PMID: 30539638 DOI: 10.1021/acs.nanolett.8b03891] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Modal gain coefficient is a key figure of merit for a laser material. Previously, net modal gain coefficients larger than a few thousand cm-1 were achieved in II-VI and III-V semiconductor gain media, but this required operation at cryogenic temperatures. In this work, using pump-fluence-dependent variable-stripe-length measurements, we show that colloidal CdSe nanoplatelets enable giant modal gain coefficients at room temperature up to 6600 cm-1 under pulsed optical excitation. Furthermore, we show that exceptional gain performance is common to the family of CdSe nanoplatelets, as shown by examining samples having different vertical thicknesses and lateral areas. Overall, colloidal II-VI nanoplatelets with superior optical gain properties are promising for a broad range of applications, including high-speed light amplification and loss compensation in plasmonic photonic circuits.
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Affiliation(s)
- Burak Guzelturk
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
| | - Matthew Pelton
- Department of Physics , University of Maryland, Baltimore County , Baltimore , Maryland 21250 , United States
| | - Murat Olutas
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
- Department of Physics , Bolu Abant Izzet Baysal University , Bolu 14030 , Turkey
| | - Hilmi Volkan Demir
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering , Nanyang Technological University , Nanyang Avenue , Singapore 639798 , Singapore
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