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Lin L, Liu AA, Zhao W, Yang Y, Zhu DL, Dong BR, Ding F, Ning D, Zhu X, Liu D, Pang DW. Multihierarchical Regulation To Achieve Quantum Dot Nanospheres with a Photoluminescence Quantum Yield Close to 100. J Am Chem Soc 2024. [PMID: 38905206 DOI: 10.1021/jacs.4c03308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
Quantum dots (QDs) exhibit superior brightness and photochemical stability, making them the preferred option for highly sensitive single-molecule detection compared with fluorescent dyes or proteins. Nevertheless, their high surface energy leads to nonspecific adsorption and poor colloidal stability. In the past decades, we have found that QD-based fluorescent nanoparticles (FNs) can not only address these limitations but also enhance detection sensitivity. However, the photoluminescence quantum yield (PLQY) of FNs is significantly lower compared with that of original QDs. It is urgent to develop a strategy to solve the issue, aiming to further enhance detection sensitivity. In this study, we found that the decrease of PLQY of FNs prepared by free radical polymerization was attributed to two factors: (1) generation of defects that can cause nonradiative transitions resulting from QD-ligands desorption and QD-shell oxidation induced by free radicals; (2) self-absorption resulting from aggregation caused by incompatibility of QDs with polymers. Based on these, we proposed a multihierarchical regulation strategy that includes: (1) regulating QD-ligands; (2) precisely controlling free radical concentration; and (3) constructing cross-linked structures of polymer to improve compatibility and to reduce the formation of surface defects. It is crucial to emphasize that the simultaneous coordination of multiple factors is essential. Consequently, a world-record PLQY of 97.6% for FNs was achieved, breaking through the current bottleneck at 65%. The flexible application of this regulatory concept paves the way for the large-scale production of high-brightness QD-polymer complexes, enhancing their potential applications in sensitive biomedical detection.
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Affiliation(s)
- Leping Lin
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - An-An Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Wei Zhao
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Yin Yang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Dong-Liang Zhu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Bo-Ran Dong
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Fei Ding
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Di Ning
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Xiaobo Zhu
- Cannano Jiayuan (Guangzhou) Science & Technology Co., Ltd, Guangzhou 510700, P. R. China
| | - Dingbin Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
| | - Dai-Wen Pang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Center for New Organic Matter, Research Center for Analytical Sciences, College of Chemistry, Frontiers Science Center for Cell Responses, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Engineering Research Center of Thin Film Optoelectronics Technology, Ministry of Education, Tianjin 300071, P. R. China
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Lei H, Li J, Kong X, Wang L, Peng X. Toward Surface Chemistry of Semiconductor Nanocrystals at an Atomic-Molecular Level. Acc Chem Res 2023. [PMID: 37413974 DOI: 10.1021/acs.accounts.3c00185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
ConspectusProperties of colloidal semiconductor nanocrystals with a single-crystalline structure are largely dominated by their surface structure at an atomic-molecular level, which is not well understood and controlled, due to a lack of experimental tools. However, if viewing the nanocrystal surface as three relatively independent spatial zones (i.e., crystal facets, inorganic-ligands interface, and ligands monolayer), we may approach an atomic-molecular level by coupling advanced experimental techniques and theoretical calculations.Semiconductor nanocrystals of interest are mainly based on compound semiconductors and mostly in two (or related) crystal structures, namely zinc-blende and wurtzite, which results in a small group of common low-index crystal facets. These low-index facets, from a surface-chemistry perspective, can be further classified into polar and nonpolar ones. Albeit far from being successful, the controlled formation of either polar or nonpolar facets is available for cadmium chalcogenide nanocrystals. Such facet-controlled systems offer a reliable basis for studying the inorganic-ligands interface. For convenience, here facet-controlled nanocrystals refer to a special class of shape-controlled ones, in which shape control is at an atomic level, instead of those with poorly defined facets (e.g., typical spheroids, nanorods, etc).Experimental and theoretical results reveal that type and bonding mode of surface ligands on nanocrystals is facet-specific and often beyond Green's classification (X-type, Z-type, and L-type). For instance, alkylamines bond strongly to the anion-terminated (0001) wurtzite facet in the form of ammonium ions, with three hydrogens of an ammonium ion bonding to three adjacent surface anion sites. With theoretically assessable experimental data, facet-ligands pairing can be identified using density functional theory (DFT) calculations. To make the pairing meaningful, possible forms of all potential ligands in the system need to be examined systematically, revealing the advantage of simple solution systems.Unlike the other two spatial zones, the ligands monolayer is disordered and dynamic at an atomic level. Thus, an understanding of the ligands monolayer on a molecular scale is sufficient for many cases. For colloidal nanocrystals stably coordinated with surface ligands, their solution properties are dictated by the ligands monolayer. Experimental and theoretical results reveal that solubility of a nanocrystal-ligands complex is an interplay between the intramolecular entropy of the ligands monolayer and intermolecular interactions of the ligands/nanocrystals. By introducing entropic ligands, solubility of nanocrystal-ligands complexes can be universally boosted by several orders of magnitude, i.e., up to >1 g/mL in typical organic solvents. Molecular environment in the pseudophase surrounding each nanocrystal plays a critical role in its chemical, photochemical, and photophysical properties.For some cases, such as the synthesis of high-quality nanocrystals, all three spatial zones of the nanocrystal surface must be taken into account. By optimizing nanocrystal surface at an atomic-molecular level, semiconductor nanocrystals with monodisperse size and facet structure become available recently through either direct synthesis or afterward facet reconstruction, implying full realization of their size-dependent properties.
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Affiliation(s)
- Hairui Lei
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou, 310058, China
| | - Jiongzhao Li
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou, 310058, China
| | - Xueqian Kong
- Institute of Translational Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Linjun Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou, 310058, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province, and Department of Chemistry, Zhejiang University, Hangzhou, 310058, China
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Huang B, Huang Y, Zhang H, Lu X, Gao X, Zhuang S. Electrochemical Control over the Optical Properties of II-VI Colloidal Nanoplatelets by Tailoring the Station of Extra Charge Carriers. ACS APPLIED MATERIALS & INTERFACES 2023; 15:21354-21363. [PMID: 37071128 DOI: 10.1021/acsami.2c21071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An electrochemical (EC) method has been successfully applied to regulate the optical properties of nanocrystals, such as reducing their gain threshold by EC doping and enhancing their photoluminescence intensity by EC filling of trap states. However, the processes of EC doping and filling are rarely reported simultaneously in a single study, hindering the understanding of their underlying interactions. Here, we report the spectroelectrochemical (SEC) studies of quasi-two-dimensional nanoplatelets (NPLs), intending to clarify the above issues. EC doping is successfully achieved in CdSe/CdZnS core/shell NPLs, with red-shifted photoluminescence and a reversal of the emission intensity trend. The injection of extra electrons (holes) into the conduction (valence) band edges needs high bias voltages, while the passivation/activation process of trap states with the shift of Fermi level starts at lower EC potentials. Then, we explore the role of excitation light conditions in these processes, different from existing SEC research studies. Interestingly, increasing the laser power density can hinder EC electron injection, whereas decreasing the excitation energy evades the passivation process of trap states. Moreover, we demonstrate that EC control strategies can be used to realize color display and anti-counterfeiting applications via simultaneously tailoring the photoluminescence intensity of red- and green-emitting NPLs.
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Affiliation(s)
- Bo Huang
- Institute of Carbon Neutrality and New Energy, School of Electronics and Information, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, P.R. China
| | - Yihuai Huang
- Institute of Carbon Neutrality and New Energy, School of Electronics and Information, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, P.R. China
| | - Huichao Zhang
- Institute of Carbon Neutrality and New Energy, School of Electronics and Information, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, P.R. China
| | - Xinmiao Lu
- Institute of Carbon Neutrality and New Energy, School of Electronics and Information, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, P.R. China
| | - Xiumin Gao
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Songlin Zhuang
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
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Lei H, Li T, Li J, Zhu J, Zhang H, Qin H, Kong X, Wang L, Peng X. Reversible Facet Reconstruction of CdSe/CdS Core/Shell Nanocrystals by Facet-Ligand Pairing. J Am Chem Soc 2023; 145:6798-6810. [PMID: 36942751 DOI: 10.1021/jacs.2c13500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Synthesis of colloidal semiconductor nanocrystals with defined facet structures is challenging, though such nanocrystals are essential for fully realizing their size-dependent optical and optoelectronic properties. Here, for the mostly developed colloidal wurtzite CdSe/CdS core/shell nanocrystals, facet reconstruction is investigated under typical synthetic conditions, excluding nucleation, growth, and interparticle ripening. Within the reaction time window, two reproducible sets of facets─each with a specific group of low-index facets─can be reversibly reconstructed by switching the ligand system, indicating thermodynamic stability of each set. With a unique <0001> axis, atomic structures of the low-index facets of wurtzite nanocrystals are diverse. Experimental and theoretical studies reveal that each facet in a given set is paired with a common ligand in the solution, namely, either fatty amine and/or cadmium alkanoate. The robust bonding modes of ligands are found to be strongly facet-dependent and often unconventional, instead of following Green's classification. Results suggest that facet-controlled nanocrystals can be synthesized by optimal facet-ligand pairing either in synthesis or after-synthesis reconstruction, implying semiconductor nanocrystal formation with size-dependent properties down to an atomic level.
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Affiliation(s)
- Hairui Lei
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Tenghui Li
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Jiongzhao Li
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Jie Zhu
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Haibing Zhang
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Haiyan Qin
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Xueqian Kong
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Linjun Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Xiaogang Peng
- Key Laboratory of Excited-State Materials of Zhejiang Province and Department of Chemistry, Zhejiang University, Hangzhou 310058, China
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5
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McIsaac AR, Goldzak T, Van Voorhis T. It Is a Trap!: The Effect of Self-Healing of Surface Defects on the Excited States of CdSe Nanocrystals. J Phys Chem Lett 2023; 14:1174-1181. [PMID: 36715489 DOI: 10.1021/acs.jpclett.2c03317] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Colloidal semiconductor nanocrystals have attracted much interest due to their unique optical properties, with applications ranging from displays to biomedical imaging. Nanocrystal optical properties depend on the structure of the surface, where defects can lead to traps. CdSe nanocrystals undergo surface reorganization, or self-healing, to eliminate defects, removing midgap traps from the band structure. However, the effect of this process on the optical spectrum is not well studied. Here, we show that self-healing not only eliminates midgap traps from the band structure but also brightens the spectrum and causes the excitonic states to emerge as the dominant features, in agreement with experimental annealing studies. We find that self-healing can lead to new traps like bonded Se-Se or Cd-Cd dimers, and their behavior is different from that of undercoordinated atom traps. These results suggest that eliminating traps requires a balance of allowing enough surface reorganization to eliminate undercoordinated atoms, but not so much that dimeric traps form.
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Affiliation(s)
- Alexandra R McIsaac
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tamar Goldzak
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Wang N, Cheong S, Yoon DE, Lu P, Lee H, Lee YK, Park YS, Lee DC. Efficient, Selective CO 2 Photoreduction Enabled by Facet-Resolved Redox-Active Sites on Colloidal CdS Nanosheets. J Am Chem Soc 2022; 144:16974-16983. [PMID: 36007150 DOI: 10.1021/jacs.2c06164] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Advances in nanotechnology have enabled precise design of catalytic sites for CO2 photoreduction, pushing product selectivity to near unity. However, activity of most nanostructured photocatalysts remains underwhelming due to fast recombination of photogenerated electron-hole pairs and sluggish hole transfer. To address these issues, we construct colloidal CdS nanosheets (NSs) with the large basal planes terminated by S2- atomic layers as intrinsic photocatalysts (CdS-S2- NSs). Experimental investigation reveals that the S2- termination endows ultrathin CdS-S2- NSs with facet-resolved redox-catalytic sites: oxidation occurs on S2--terminated large basal facets and reduction happens on side facets. Such an allocation of redox sites not only promotes spatial separation of photoinduced electrons and holes but also facilitates balanced extraction of holes and electrons by shortening the hole diffusion distance along the (001) direction of the ultrathin NSs. Consequently, the CdS-S2- NSs exhibit superb performance for photocatalytic CO2-to-CO conversion, which was verified by the isotope-labeled experiments to be a record-breaking performance: a CO selectivity of 99%, a CO formation rate of 2.13 mol g-1 h-1, and an effective apparent quantum efficiency of 42.1% under the irradiation (340 to 450 nm) of a solar simulator (AM 1.5G). The breakthrough performance achieved in this work provides novel insights into the precise design of nanostructures for selective and efficient CO2 photoreduction.
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Affiliation(s)
- Nianfang Wang
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Energy & Environmental Research Center (EERC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Seokhyeon Cheong
- Division of Energy and Environment Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Republic of Korea
| | - Da-Eun Yoon
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Energy & Environmental Research Center (EERC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Pan Lu
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Energy & Environmental Research Center (EERC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hyunjoo Lee
- Division of Energy and Environment Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Republic of Korea.,Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Young Kuk Lee
- Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
| | - Young-Shin Park
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Energy & Environmental Research Center (EERC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Doh C Lee
- Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury, Energy & Environmental Research Center (EERC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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