Tuning the surface properties of alloyed CdS<sub>x</sub>Se<sub>1−x</sub> 2D nanosheets

Maiti, Pradipta Sankar; Bar‐Sadan, Maya

doi:10.1039/c5ra22014a

Cited by 9 publications

(7 citation statements)

References 41 publications

(54 reference statements)

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“…CdS is also discussed previously as a wide band gap bulk semiconductor (∼2.4 eV) . Several studies have investigated the synthesis and characterization of colloidal 2D nanosheets of CdS and CdS 1– x Se x . , CdS nanosheets and nanoparticles have been intensively studied for photocatalysis by assembling into heterojunctions with other 2D materials, for example, graphene/graphene oxide, − MoS 2 , , ZnSe, etc., and monolayers or nanosheets can be stacked sequentially to form heterostructures. CdS/ZnSe in-plane heterostructures are predicted by HSE06 to have type-II band alignment and 2.31 eV direct band gap with the “armchair configuration”, with predicted electron and hole mobilities of ∼884 and ∼1920 cm 2 V –1 s –1 , respectively …”

Section: Methodsmentioning

confidence: 99%

Wide Band Gap Chalcogenide Semiconductors

et al. 2020

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Wide band gap semiconductors are essential for today's electronic devices and energy applications due to their high optical transparency, as well as controllable carrier concentration and electrical conductivity. There are many categories of materials that can be defined as wide band gap semiconductors. The most intensively investigated are transparent conductive oxides (TCOs) such as tin-doped indium oxide (ITO) and amorphous In-Ga-Zn-O (IGZO) used in displays, carbides (e.g. SiC) and nitrides (e.g. GaN) used in power electronics, as well as emerging halides (e.g. g-CuI) and 2D electronic materials (e.g. graphene) used in various optoelectronic devices. Compared to these prominent materials families, chalcogen-based (Ch = S, Se, Te) wide band gap semiconductors are less heavily investigated but stand out due to their propensity for ptype doping, high mobilities, high valence band positions (i.e. low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide band gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent conductors, as well as the theoretical and experimental underpinnings of the corresponding research methods. We proceed to summarize progress in wide band gap (E G > 2 eV) chalcogenide materials, such as II-VI MCh binaries, CuMCh 2 chalcopyrites, Cu 3 MCh 4 sulvanites, mixed anion layered CuMCh(O,F), and 2D materials, among others, and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications of chalcogenide wide band gap semiconductors, e.g. photovoltaic and photoelectrochemical solar cells, transparent transistors, and light emitting diodes, that employ wide band gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide band gap chalcogenides, this review aims to inspire continued research on this emerging class of transparent conductors and to enable future innovations for optoelectronic devices.

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Section: Methodsmentioning

confidence: 99%

Wide Band Gap Chalcogenide Semiconductors

et al. 2020

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“…To achieve further tunable excitonic properties in colloidal NPLs, homogeneous alloying can be used as a highly effective approach, which has not been studied extensively. Previously, several studies have reported the synthesis of homogeneously alloyed CdSe x S 1– x core-only NPLs, showing tunable absorption spectra by adjusting the sulfur compositions. , However, the synthesized CdSe x S 1– x core-only NPLs exhibit low PL-QY (∼10–20%) with the limited emission tunability in the spectral range of ∼490–510 nm . Therefore, engineered heterostructures of alloyed NPLs have been greatly required to obtain enhanced excitonic properties, enabling the achievement of highly tunable and low-threshold gain performance.…”

Section: Introductionmentioning

confidence: 99%

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

et al. 2017

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Here, we designed and synthesized alloyed heterostructures of CdSe x S1–x nanoplatelets (NPLs) using CdS coating in the lateral and vertical directions for the achievement of highly tunable optical gain performance. By using homogeneously alloyed CdSe x S1–x core NPLs as a seed, we prepared CdSe x S1–x /CdS core/crown NPLs, where CdS crown region is extended only in the lateral direction. With the sidewall passivation around inner CdSe x S1–x cores, we achieved enhanced photoluminescence quantum yield (PL-QY) (reaching 60%), together with increased absorption cross-section and improved stability without changing the emission spectrum of CdSe x S1–x alloyed core NPLs. In addition, we further extended the spectral tunability of these solution-processed NPLs with the synthesis of CdSe x S1–x /CdS core/shell NPLs. Depending on the sulfur composition of the CdSe x S1–x core and thickness of the CdS shell, CdSe x S1–x /CdS core/shell NPLs possessed highly tunable emission characteristics within the spectral range of 560–650 nm. Finally, we studied the optical gain performances of different heterostructures of CdSe x S1–x alloyed NPLs offering great advantages, including reduced reabsorption and spectrally tunable optical gain range. Despite their decreased PL-QY and reduced absorption cross-section upon increasing the sulfur composition, CdSe x S1–x based NPLs exhibit highly tunable amplified spontaneous emission performance together with low gain thresholds down to ∼53 μJ/cm2.

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“…Both the growth mechanisms and the final objects are very different for these two crystal structures. In the case of WZ nanoparticles, a lamellar-like template growth with a cadmium chloride alkylamine complex serving as a mold during the formation of WZ CdSe 2D nanostructures has been evidenced. − These nanoparticles aggregate easily, have weakly bound ligands, and have a balanced number of anions and cations. On the contrary, CdSe NPLs with a cubic ZB crystal structure have an excess of cations, controllable lateral extension from few nanometers to a micrometer and good colloidal stability, thanks to carboxylate ligands bound onto the two cadmium-rich large base facets.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

Jiang

Ojo²,

Mahler

et al. 2018

ACS Omega

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We present a novel route for the synthesis of zinc blende CdSe nanoplatelets (NPLs) that exclude the use of short-chain alkyl carboxylates. CdSe NPLs obtained without acetates are shown to be extremely asymmetric and rectangular. The effects of several experimental parameters such as the nature of cadmium carboxylates, selenium precursors, and precursor concentration ratios are studied. Our experiments, together with complementary small-/wide-angle X-ray scattering results, show that the formation of NPLs is not related to soft templating. We discuss our findings in regard to several other formation mechanisms of NPLs, which have appeared recently in the literature, and propose that the steric hindrance caused by ligand packing exerts an influence on the growth and geometry of two-dimensional NPLs.

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Tuning the surface properties of alloyed CdS_xSe_1−x 2D nanosheets

Abstract: Surface engineering and tuning of the optoelectronic properties of wurtzite CdSxSe1−x nanosheets by ligand exchange.

Cited by 9 publications

References 41 publications

Wide Band Gap Chalcogenide Semiconductors

Wide Band Gap Chalcogenide Semiconductors

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

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Tuning the surface properties of alloyed CdSxSe1−x 2D nanosheets

Abstract: Surface engineering and tuning of the optoelectronic properties of wurtzite CdSxSe1−x nanosheets by ligand exchange.

Cited by 9 publications

References 41 publications

Wide Band Gap Chalcogenide Semiconductors

Wide Band Gap Chalcogenide Semiconductors

Alloyed Heterostructures of CdSexS1–x Nanoplatelets with Highly Tunable Optical Gain Performance

Synthesis of CdSe Nanoplatelets without Short-Chain Ligands: Implication for Their Growth Mechanisms

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Tuning the surface properties of alloyed CdS_xSe_1−x 2D nanosheets

Alloyed Heterostructures of CdSe_xS_1–x Nanoplatelets with Highly Tunable Optical Gain Performance