Phosphine-Free Synthesis of CdSe Nanocrystals

Jasieniak, Jacek J.; Bullen, Craig; Embden, Joel van; Mulvaney, Paul

doi:10.1021/jp054289o

Cited by 235 publications

(263 citation statements)

References 17 publications

(26 reference statements)

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“…A cadmium oleate (Cd-OA) stock solution was prepared by first degassing 9.3 mmol (1.2 g) of CdO and 106 mmol (30 g) of oleic acid in 120 g of 1-octadecene (ODE) at 100 1C for 30 min 43 . This solution was heated to 300 1C under nitrogen until it became transparent and homogeneous.…”

Section: Methodsmentioning

confidence: 99%

Magneto-optical properties of trions in non-blinking charged nanocrystals reveal an acoustic phonon bottleneck

et al. 2012

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Charged quantum dots provide an important platform for a range of emerging quantum technologies. Colloidal quantum dots in particular offer unique advantages for such applications (facile synthesis, manipulation and compatibility with a wide range of environments), especially if stable charged states can be harnessed in these materials. Here we engineer the CdSe nanocrystal core and shell structure to efficiently ionize at cryogenic temperatures, resulting in trion emission with a single sharp zero-phonon line and a mono exponential decay. Magneto-optical spectroscopy enables direct determination of electron and hole g-factors. Spin relaxation is observed in high fields, enabling unambiguous identification of the trion charge. Importantly, we show that spin flips are completely inhibited for Zeeman splittings below the low-energy bound for confined acoustic phonons. This reveals a characteristic unique to colloidal quantum dots that will promote the use of these versatile materials in challenging quantum technological applications.

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Section: Methodsmentioning

confidence: 99%

Magneto-optical properties of trions in non-blinking charged nanocrystals reveal an acoustic phonon bottleneck

et al. 2012

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“…Os nanocristais de CdSe obtidos desta forma apresentaram uma baixa distribuição de tamanhos (menor que 5%) e uma estrutura cristalina do tipo blenda de zinco. 19,20 Uma última simplificação foi proposta por Sapra et al, 21 que utilizaram óleo de oliva como meio reacional para os precursores CdO e selênio elementar. A possibilidade de dissolver CdO em óleo de oliva foi, posteriormente, empregada para produção de nanocristais de CdSe, com tamanhos de 2,3 a 6,0 nm, utilizando ácido oleico (AO) como solvente da reação.…”

Section: Figura 2 Principais Etapas Envolvidas Nas Sínteses De Semicunclassified

O estado da arte da síntese de semicondutores nanocristalinos coloidais

et al. 2010

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, 74, 36301-160 São João del-Rei -MG, Brasil Recebido em 8/11/09; aceito em 21/4/10; publicado na web em 24/8/10 THE STATE OF THE ART IN THE SYNTHESIS OF COLLOIDAL SEMICONDUCTOR NANOCRYSTALS. Colloidal semiconductor nanocrystals, also known as quantum dots, have attracted great attention since they have interesting size-dependent properties due to the quantum confinement effect. These nanoparticles are highly luminescent and have potential applications in different technological areas, including biological labeling, light-emitting diodes and photovoltaic devices. The synthetic methods of semiconductor nanocrystals have progressed in the last 30 years, and several protocols were developed to synthesize monodisperse nanocrystals with good optical properties, different compositions and morphologies. This review describes the main methods used to synthesize nanocrystals in the II-VI and III-V systems, and the recent approaches in this field of research.Keywords: semiconductor nanocrystals; quantum dots; colloidal synthesis. INTRODUÇÃOA síntese de nanocristais, partículas cristalinas com tamanhos de 1 a 100 nm, tem sido o objeto de inúmeros trabalhos científicos no mundo todo, devido às suas intrigantes propriedades ópticas. Dentre os materiais nanométricos, têm-se os semicondutores nanocristalinos coloidais, também chamados de pontos quânticos, os quais apresentam os portadores de carga (buracos e elétrons) em um estado de forte confinamento quântico, o que faz com que estes materiais possuam propriedades ópticas que podem ser alteradas modificando-se apenas o tamanho das nanopartículas. Uma das propriedades ópticas mais interessantes destes nanocristais, do ponto de vista da aplicação tecnológica, é a forte intensidade de luminescência que apresentam, permitindo que sejam utilizados em dispositivos optoeletrônicos, fotovoltaicos e biomédicos, dentre outros. 1,2A Figura 1 apresenta imagens de dispersões coloidais aquosas de nanocristais de telureto de cádmio (CdTe) com diferentes cores de emissão, em função do tamanho das nanopartículas, bem como os espectros de absorção óptica (UV-Vis) e de fotoluminescência (PL) dessas amostras.3 Na Figura 1b é possível observar um deslocamento da banda de absorção óptica fundamental de 480 para 556 nm (red shift), devido à formação de partículas maiores ao longo da evolução da síntese. De maneira semelhante, na Figura 1c, fica evidente um deslocamento das bandas de emissão em direção a comprimentos de ondas maiores, de 507 nm da primeira amostra para 592 nm na última amostra, o que corresponde a uma variação nas cores de emissão, como mostrado na Figura 1a.Os semicondutores nanocristalinos podem ser divididos em diferentes grupos da tabela periódica, tais como II-VI, III-V e IV-VI, sendo que, nesta revisão, são abordados, principalmente, os métodos experimentais de síntese para produção dos semicondutores dos grupos II-VI e III-V, embora esse último grupo seja ainda muito menos estudado. As sínteses destes materiais podem ser realizadas pelo método top-down, que utiliza técnicas ...

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“…[17][18][19] It was considered that TOPO is an essential requirement for producing highly mono-disperse II-VI semiconductor nanocrystals, however, TOPO may generate unknown pollutants. [23][24][25][26][27] Further, the TOPO could be replaced by a non-coordinating solvent octadecene (ODE) and produces mono-dispersed nanocrystals of CdSe. [17][18][19][20][21][22][23][24][25][26] In addition to the non-coordinating solvent ODE, a supporting solvent trimethylpentyl phosphinic acid (TMPPA), hexadecayl amine (HDA) and tributyl phosphine (TBP) were also used to control the reaction condition.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the replacement of TOPO makes the synthesis less expensive, safer and greener in comparison to the other solvents. [17][18][19][20][21][22][23][24][25][26] Therefore, to make environmental friendly Q-dots less use of TOPO is desirable. In this report, we prepared CdSe Q-dots in TOPO free environment at varying temperature of 240 -300…”

Section: Introductionmentioning

confidence: 99%

Controlled synthesis and optical properties of tunable CdSe quantum dots and effect of pH

Ratnesh

Mehata

2015

AIP Advances

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Cadmium selenide (CdSe) quantum dots (Q-dots) were prepared by using non-coordinating solvent octadecene instead of coordinating agent trioctylphosphine oxide (TOPO). Reaction processes were carried out at various temperatures of 240°, 260°, 280° and 300° C under nitrogen atmosphere. The prepared CdSe Q-dots which are highly stable show uniform size distribution and tunable optical absorption and photoluminescence (PL). The growth temperature significantly influenced the particle size; spectral behavior, energy band gap and PL intensity and the full width at half maxima (FWHM). Three different methods were employed to determine the particle size and the average particle size of the CdSe Q-dots is 3.2 - 4.3 nm, grown at different temperatures. In addition, stable and mono-dispersed water soluble CdSe Q-dots were prepared by the ligand exchange technique. Thus, the water soluble Q-dots, which are sensitive to the basic pH may be important for biological applications.

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Phosphine-Free Synthesis of CdSe Nanocrystals

Cited by 235 publications

References 17 publications

Magneto-optical properties of trions in non-blinking charged nanocrystals reveal an acoustic phonon bottleneck

Magneto-optical properties of trions in non-blinking charged nanocrystals reveal an acoustic phonon bottleneck

O estado da arte da síntese de semicondutores nanocristalinos coloidais

Controlled synthesis and optical properties of tunable CdSe quantum dots and effect of pH

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