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Chou KC, Li LC, Tsai KA, Zeitz DC, Pu YC, Zhang JZ. Effect of Lattice Disorder on Exciton Dynamics in Copper-Doped InP/ZnSe xS 1-x Core/Shell Quantum Dots. J Phys Chem Lett 2024; 15:4311-4318. [PMID: 38619190 DOI: 10.1021/acs.jpclett.4c00689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
InP/ZnSexS1-x core/shell quantum dots (QDs) with varying Cu concentrations were synthesized by a one-pot hot-injection method. X-ray diffraction and high-resolution transmission electron microscopy results indicate that Cu doping did not alter the crystal structure or particle size of the QDs. The optical shifts in UV-visible absorption and photoluminescence (PL) suggest changes in the electronic structure and induction of lattice disorder due to Cu doping. Ultrafast transient absorption spectroscopy (TAS) reveled that a higher Cu-doping level leads to faster charge carrier recombination, likely due to increased nonradiative decay from defect states. Time-resolved PL (TRPL) studies show longer average lifetimes of charge carriers with increased Cu doping. These findings informed the development of a kinetic model to better understand how Cu-induced disorder affects charge carrier dynamics in the QDs, which is important for emerging applications of Cu-doped InP/ZnSexS1-x QDs in optoelectronics.
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Affiliation(s)
- Kai-Chun Chou
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Le-Chun Li
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Kai-An Tsai
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - David C Zeitz
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Ying-Chih Pu
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Jin Z Zhang
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
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2
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Ruhman S. Solving Quantum-Dot Excitonic Riddles with Absolute Pump-Probe Spectroscopy. J Phys Chem Lett 2021; 12:9336-9343. [PMID: 34549584 DOI: 10.1021/acs.jpclett.1c02408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Absolute absorption changes in molecular flash photolysis experiments are routinely translated into molar extinction coefficients and oscillator strengths of reactive intermediates. These direct quantum chemical investigation and allow precise concentration readings in later experiments. In this Perspective we show how a similar approach can deliver crucial information for interpreting transient absorption spectra in colloidal semiconductor quantum dots. The intrinsic complexity of such samples stemming from the inhomogeneity of particle size, shape, and surface chemistry poses unique challenges to mechanistic assignment of ultrafast pump-probe measurements. We will describe applications of this approach to elucidate the photophysics of quantum confined nanocrystals made of various semiconducting materials. These case studies demonstrate how, faced with conflicting interpretations, it has pointed in the right direction in assessing single and multiple exciton generation and relaxation, in searches for ultrafast carrier trapping and scavenging, and in tests of band edge level structure and state degeneracies.
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Affiliation(s)
- Sanford Ruhman
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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Capitani C, Pinchetti V, Gariano G, Santiago-González B, Santambrogio C, Campione M, Prato M, Brescia R, Camellini A, Bellato F, Carulli F, Anand A, Zavelani-Rossi M, Meinardi F, Crooker SA, Brovelli S. Quantized Electronic Doping towards Atomically Controlled "Charge-Engineered" Semiconductor Nanocrystals. NANO LETTERS 2019; 19:1307-1317. [PMID: 30663314 DOI: 10.1021/acs.nanolett.8b04904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
"Charge engineering" of semiconductor nanocrystals (NCs) through so-called electronic impurity doping is a long-standing challenge in colloidal chemistry and holds promise for ground-breaking advancements in many optoelectronic, photonic, and spin-based nanotechnologies. To date, our knowledge is limited to a few paradigmatic studies on a small number of model compounds and doping conditions, with important electronic dopants still unexplored in nanoscale systems. Equally importantly, fine-tuning of charge engineered NCs is hampered by the statistical limitations of traditional approaches. The resulting intrinsic doping inhomogeneity restricts fundamental studies to statistically averaged behaviors and complicates the realization of advanced device concepts based on their advantageous functionalities. Here we aim to address these issues by realizing the first example of II-VI NCs electronically doped with an exact number of heterovalent gold atoms, a known p-type acceptor impurity in bulk chalcogenides. Single-dopant accuracy across entire NC ensembles is obtained through a novel non-injection synthesis employing ligand-exchanged gold clusters as "quantized" dopant sources to seed the nucleation of CdSe NCs in organic media. Structural, spectroscopic, and magneto-optical investigations trace a comprehensive picture of the physical processes resulting from the exact doping level of the NCs. Gold atoms, doped here for the first time into II-VI NCs, are found to incorporate as nonmagnetic Au+ species activating intense size-tunable intragap photoluminescence and artificially offsetting the hole occupancy of valence band states. Fundamentally, the transient conversion of Au+ to paramagnetic Au2+ (5d9 configuration) under optical excitation results in strong photoinduced magnetism and diluted magnetic semiconductor behavior revealing the contribution of individual paramagnetic impurities to the macroscopic magnetism of the NCs. Altogether, our results demonstrate a new chemical approach toward NCs with physical functionalities tailored to the single impurity level and offer a versatile platform for future investigations and device exploitation of individual and collective impurity processes in quantum confined structures.
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Affiliation(s)
- Chiara Capitani
- Glass to Power SpA, Via Fortunato Zeni 8 , I-38068 Rovereto, , Italy
| | | | - Graziella Gariano
- Glass to Power SpA, Via Fortunato Zeni 8 , I-38068 Rovereto, , Italy
| | - Beatriz Santiago-González
- International Iberian Nanotechnology Laboratory, Nanophotonics Department , Ultrafast Bio- and Nanophotonics Group , Avenida Mestre José Veiga s/n , 4715-330 Braga , Portugal
| | - Carlo Santambrogio
- Dipartimento di Biotecnologie e Bioscienze , Università degli Studi di Milano-Bicocca , Piazza della Scienza 2 , I-20126 Milano , Italy
| | | | - Mirko Prato
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
| | - Rosaria Brescia
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
| | - Andrea Camellini
- Dipartimento di Energia , Politecnico di Milano and IFN-CNR , Milano , Italy
| | | | | | | | | | | | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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Mehta A, Im J, Kim BH, Min H, Nie R, Seok SI. Stabilization of Lead-Tin-Alloyed Inorganic-Organic Halide Perovskite Quantum Dots. ACS NANO 2018; 12:12129-12139. [PMID: 30525444 DOI: 10.1021/acsnano.8b05478] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Recently, lead-tin-based alloyed halide perovskite quantum dots (QDs) with improved stability and less toxicity have been introduced. However, the perovskite QDs containing tin are still unstable and exhibit low photoluminescence quantum yields (PLQYs), owing to the presence of defects in the alloyed system. Here, we have attempted to introduce sulfur anions (S2-) into the host lattice (MAPb0.75Sn0.25Br3) as a promising route to stable alloyed perovskite QDs with improved stability and PLQY. In this study, we used elemental sulfur as a sulfur precursor. The successful incorporation of sulfur anions into the host lattice resulted in a highly improved PLQY (>75% at room temperature), which is believed to be due to a reduction in the defect-related non-radiative recombination centers present in the host lattice. Furthermore, we found that the emission property could be tuned between the bright green and cyan-bluish regions without compromising on color quality. This work invigorates the perovskite research community to prepare stable, bright, and color-tunable alloyed inorganic-organic perovskite QDs without compromising on their phases and color quality, which can lead to considerable advances in display technology.
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Affiliation(s)
- Aarti Mehta
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Eonyang-eup, Ulju-gun, Ulsan 44919 , Republic of Korea
| | - Jino Im
- Division of Advanced Materials , Korea Research Institute of Chemical Technology , 141 Gajeong-Ro , Yuseong-Gu, Deajeon 34114 , Republic of Korea
| | - Bo Hyung Kim
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Eonyang-eup, Ulju-gun, Ulsan 44919 , Republic of Korea
| | - Hanul Min
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Eonyang-eup, Ulju-gun, Ulsan 44919 , Republic of Korea
| | - Riming Nie
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Eonyang-eup, Ulju-gun, Ulsan 44919 , Republic of Korea
| | - Sang Il Seok
- Perovtronics Research Center, Department of Energy Engineering, School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Eonyang-eup, Ulju-gun, Ulsan 44919 , Republic of Korea
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5
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Hughes KE, Hartstein KH, Gamelin DR. Photodoping and Transient Spectroscopies of Copper-Doped CdSe/CdS Nanocrystals. ACS NANO 2018; 12:718-728. [PMID: 29286633 DOI: 10.1021/acsnano.7b07879] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Colloidal Cu+-doped CdSe/CdS core/shell semiconductor nanocrystals (NCs) are investigated in their as-prepared and degenerately n-doped forms using time-resolved photoluminescence and transient-absorption spectroscopies. Photoluminescence from Cu+:CdSe/CdS NCs is dominated by recombination of delocalized conduction-band (CB) electrons with copper-localized holes. In addition to prominent bleaching of the first excitonic absorption feature, transient-absorption measurements show bleaching of the sub-bandgap copper-to-CB charge-transfer (MLCBCT) absorption band and also reveal a photoinduced midgap valence-band (VB)-to-copper charge-transfer (LVBMCT) absorption band that extends into the near-infrared, as predicted by recent computations. The photoluminescence of these NCs is substantially diminished upon introduction of excess CB electrons via photodoping. Time-resolved photoluminescence measurements reveal that the MLCBCT excited state is still formed upon photoexcitation of the n-doped Cu+:CdSe/CdS NCs, but its luminescence is quenched by a fast (picosecond) three-carrier trap-assisted Auger recombination process involving two CB electrons and one copper-bound hole.
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Affiliation(s)
- Kira E Hughes
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Kimberly H Hartstein
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
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6
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Faust A, Amit Y, Banin U. Phonon-Plasmon Coupling and Active Cu Dopants in Indium Arsenide Nanocrystals Studied by Resonance Raman Spectroscopy. J Phys Chem Lett 2017; 8:2519-2525. [PMID: 28524661 DOI: 10.1021/acs.jpclett.7b00661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Doping of semiconductor nanocrystals is an emerging tool to control their properties and has recently received increased interest as the means to characterize the impurities and their effect on the electronic characteristics of the nanocrystal evolve. We present a temperature-dependent Raman scattering study of Cu-doped InAs nanocrystals observing changes in the relative scattering intensities of the different modes upon increased dopant concentrations. First, the longitudinal optical (LO) phonon overtone mode is suppressed, indicating weakening of the coupling strength related to the effect of screening by the free electrons. Second, the transverse optical (TO) mode is relatively enhanced compared to the LO mode, which is attributed to the appearance of a coupled phonon-plasmon mode analogous to observations for n-type doped bulk InAs. These signatures indicate that the Cu impurities serve as active dopants and occupy an impurity-related pseudo sub-band akin to the heavy doping limit.
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Affiliation(s)
- Adam Faust
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Yorai Amit
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Uri Banin
- The Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
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7
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Begum R, Parida MR, Abdelhady AL, Murali B, Alyami NM, Ahmed GH, Hedhili MN, Bakr OM, Mohammed OF. Engineering Interfacial Charge Transfer in CsPbBr 3 Perovskite Nanocrystals by Heterovalent Doping. J Am Chem Soc 2016; 139:731-737. [PMID: 27977176 DOI: 10.1021/jacs.6b09575] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr3 perovskite NCs with heterovalent Bi3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.
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Affiliation(s)
- Raihana Begum
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Manas R Parida
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Ahmed L Abdelhady
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Banavoth Murali
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Noktan M Alyami
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Ghada H Ahmed
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Mohamed Nejib Hedhili
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Osman M Bakr
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Omar F Mohammed
- KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia
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