Ligand Exchange and Impurity Doping in 2D CdSe Nanoplatelet Thin Films and Their Applications

Lee, Woo Seok; Kang, Young Sook; Sharma, Manoj; Lee, Yong Min; Jeon, Sanghyun; Sharma, Amit; Demir, Hilmi Volkan; Han, Myung Joon; Koh, Weon-kyu; Oh, Soong Ju

doi:10.1002/aelm.202100739

Cited by 10 publications

(9 citation statements)

References 69 publications

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“…Broad emission with a large Stokes shift in semiconductors has historically been assigned to defects, − self-trapped excitons (STEs) ,− or indirect bandgap recombination. , Charge-transfer excitons can also lead to broadband emission in heterostructures with type II band alignment, − but we do not expect to observe this behavior in pure AgSePh and AgTePh. To clarify the origin of broadband emission in AgSePh and AgTePh films, we performed location- and power-dependent steady-state PL microspectroscopy.…”

Section: Resultsmentioning

confidence: 80%

Light Emission in 2D Silver Phenylchalcogenolates

et al. 2022

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Silver phenylselenolate (AgSePh, also known as “mithrene”) and silver phenyltellurolate (AgTePh, also known as “tethrene”) are two-dimensional (2D) van der Waals semiconductors belonging to an emerging class of hybrid organic–inorganic materials called metal–organic chalcogenolates. Despite having the same crystal structure, AgSePh and AgTePh exhibit a strikingly different excitonic behavior. Whereas AgSePh exhibits narrow, fast luminescence with a minimal Stokes shift, AgTePh exhibits comparatively slow luminescence that is significantly broadened and red-shifted from its absorption minimum. Using time-resolved and temperature-dependent absorption and emission microspectroscopy, combined with subgap photoexcitation studies, we show that exciton dynamics in AgTePh films are dominated by an intrinsic self-trapping behavior, whereas dynamics in AgSePh films are dominated by the interaction of band-edge excitons with a finite number of extrinsic defect/trap states. Density functional theory calculations reveal that AgSePh has simple parabolic band edges with a direct gap at Γ, whereas AgTePh has a saddle point at Γ with a horizontal splitting along the Γ-N1 direction. The correlation between the unique band structure of AgTePh and exciton self-trapping behavior is unclear, prompting further exploration of excitonic phenomena in this emerging class of hybrid 2D semiconductors.

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Section: Resultsmentioning

confidence: 80%

Light Emission in 2D Silver Phenylchalcogenolates

et al. 2022

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“…Recently, the gating of NPLs using more conventional dielectric materials has been reported . Additionally, the authors investigated using short ligands like Cl- and attempted to control the carrier density by doping with silver and copper.…”

Section: Synthesis and Structure Of Nplsmentioning

confidence: 99%

“…Recently, the gating of NPLs using more conventional dielectric materials has been reported. 456 Additionally, the authors investigated using short ligands like Cl-and attempted to control the carrier density by doping with silver and copper. In addition to bare NPLs, gold-functionalized CdSe NPLs have been evaluated as a potential strategy to tune the conductance of an array of CdSe NPLs.…”

Section: Optoelectronic Devices Based On Nanoplateletsmentioning

confidence: 99%

2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

Diroll

Güzeltürk

et al. 2023

Chem. Rev.

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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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“…To address this limitation, various mechanisms have been proposed, such as doping, the use of alloyed NPLs, and the application of external electrostatic or magnetic fields, to enhance the tunability of NPLs. One of the effective and powerful external modulating factors involves doping the sample with one or another type of impurity [18][19][20][21]. Impurity doping has long been challenging from a technological point of view and Mn doping was the most used.…”

Section: Introductionmentioning

confidence: 99%

The multi-impurity system in CdSe nanoplatelets: electronic structure and thermodynamic properties

Baghdasaryan,

Harutynyan,

Kazaryan

et al. 2024

Commun. Theor. Phys.

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This paper theoretically studies the impurity states and the effect of impurity concentration and configuration on the optical, electrical, and statistical properties of CdSe nanoplatelets (NPLs). The image charge-based model of electron–impurity interaction has been proposed. The charge carrier energy spectra and corresponding wave functions depending on impurity number and configuration have been calculated. The electron binding energies have been calculated for different NPL thicknesses. It has been shown that the image charges-based interaction potential that arises due to the dielectric constants mismatch is much stronger than the interaction potential that does not take such a mismatch into account. Also, it has been demonstrated that binding energies are increasing with the number of impurities. We calculated the canonical partition function using the energy levels of the electron, which in turn is used to obtain the mean energy, heat capacity, and entropy of the noninteracting electron gas. The thermodynamic properties of the noninteracting electron gas depending on the geometric parameters of the NPL, impurity number, configuration, and temperature have been studied.

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Ligand Exchange and Impurity Doping in 2D CdSe Nanoplatelet Thin Films and Their Applications

Cited by 10 publications

References 69 publications

Light Emission in 2D Silver Phenylchalcogenolates

Light Emission in 2D Silver Phenylchalcogenolates

2D II–VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration

The multi-impurity system in CdSe nanoplatelets: electronic structure and thermodynamic properties

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