Optically Detected Magnetic Resonance Study of CdS/HgS/CdS Quantum Dot Quantum Wells

Lifshitz, Efrat; Porteanu, Horia‐Eugen; Glozman, A.; Weller, Horst; Pflughoefft, M.; Echymueller, A.

doi:10.1021/jp990349c

Cited by 58 publications

(46 citation statements)

References 30 publications

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“…ODMR was used to detect trapped photogenerated carriers at interfacial or ligand sites; a collection of studies has been summarized in review publications. 72,167 A representative case is discussed here, [167][168][169][170][171] related to localization of a hole carrier at the surface-ligand interface. The example deals with the optical properties of CdTe CQDs capped with alkylthiols molecule.…”

Section: Topo (Ii) and Alkyl-carboxyl (Iii) Molecules Used As Typicamentioning

confidence: 99%

Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots

Lifshitz

2015

J. Phys. Chem. Lett.

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The Perspective focuses on the investigation of an unresolved conflict in semiconductor colloidal quantum dots (CQDs) research, concerning the influence of the immediate surrounding on the optical properties of the materials. Today's advanced synthetic colloidal procedures offer formation of a high-quality inorganic crystallite, capped with various organic/inorganic molecular ligands. The Perspective aims to clarify whether exciton recombination processes in CQDs are influenced by the type of crystallite-ligand bonding and, moreover, whether these excitonic processes experience direct coupling to the ligands' vibrational modes. Most ligands used have redox characteristics whose functional groups are added on to the CQDs' surface via coordination, covalent or ionic bonding. The surface-ligand bonding introduces electronic states either above or below the intraband/interband energy gap, resulting in electronic passivation or in creation of trapping states that affect intraband and interband relaxation processes. Furthermore, crystalline electronic states may have a direct coupling to molecular vibrational states via direct overlap of electronic wave functions or through a long-range energy-transfer process. Also, photoejected carriers resulting from an Auger process or ionization processes may diffuse temporarily onto a ligand site. These scenarios are discussed in the current publication with supporting theoretical and experimental observations.

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Section: Topo (Ii) and Alkyl-carboxyl (Iii) Molecules Used As Typicamentioning

confidence: 99%

Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots

Lifshitz

2015

J. Phys. Chem. Lett.

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“…Metal sulfide nano-materials have wide applications due to their optical, electrical and magnetic properties in various fields [1][2][3]. Nickel sulfides draw considerable attentions because of special properties and potential applications [4,5].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of ternary Ni1−Fe S single crystalline nanorods

Chang

Zhang

et al. 2014

Journal of Alloys and Compounds

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“…These samples were embedded in polymer films as described in Ref. [5]. The PL, ODMR measurements were carried out by immersing the samples in a cryostat (at 1.4 K) and exciting them with a continuous Ar + laser.…”

Section: Introductionmentioning

confidence: 99%

Optically Detected Spin and Orbit Resonance of Semiconductor Quantum Dots

Lifshitz

Glozman

2001

phys. stat. sol. (b)

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The luminescence spectrum of CdSe/CdS core-shell nanocrystals contains a dominant exciton band located at the CdSe core and an additional weak non-excitonic band, associated with trapped carriers. The present paper describes our efforts to identify the influence of CdSe/CdS interfaces on the localization of photogenerated species, utilizing optically detected magnetic spin and spinorbit resonance spectroscopy (ODMR). The spin resonance (SR) spectrum showed two resonance signals: the first associated with a trapped hole in a symmetric site within the core, and a second, corresponding to trapped electrons in an anisotropic interface defect site. The spin-orbit resonance (SOR) signal data are presented. IntroductionNearly two decades of research have explored the benefits of the optical and opto-electronic properties of semiconductor nanocrystals [1]. These materials exhibit unique chemical and physical properties, differing substantially from those of the corresponding bulk solids. Evidently, these differences are associated with quantumsize effects. Moreover, several recent reports have described the development of coreshell type structures [2] in which an internal semiconductor nanocrystal is coated with an epitaxial layer of a different semiconductor. These structures have shown improvements in photoluminescence (PL) quantum yields and photo-oxidative stability, as compared with the core nanocrystals. For instance, the wide band gap (2.5 eV) of CdS and narrower band gap of CdSe (1.8 eV), cause a localization of electron and hole states within the CdSe core, in a similar manner to that of a quantum well structure. While the excitonic transitions in the CdSe/CdS core-shell samples have been investigated in the last few years [3], the understanding of interface influences on the optical properties has been neglected. Indeed, for crystals in such a small size regime, a large percentage of atoms is on/near the internal interfaces or the external surfaces. These sites may act as electron and hole traps. Thus, the present work describes our attempts to clarify the optical properties associated with trapped carriers.

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Optically Detected Magnetic Resonance Study of CdS/HgS/CdS Quantum Dot Quantum Wells

Cited by 58 publications

References 30 publications

Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots

Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots

Synthesis of ternary Ni1−Fe S single crystalline nanorods

Optically Detected Spin and Orbit Resonance of Semiconductor Quantum Dots

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