Solvent-like ligand-coated ultrasmall cadmium selenide nanocrystals: strong electronic coupling in a self-organized assembly

Lawrence, Katie N.; Johnson, Merrell A.; Dolai, Sukanta; Kumbhar, Amar; Sardar, Rajesh

doi:10.1039/c5nr02038g

Cited by 16 publications

(36 citation statements)

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“…[20][21][22][23][24] A narrow size distribution would result in a sharp band-edge PL peak rather than a combination of band-edge and broadband peaks. The broad PL feature and short PL lifetimes suggest the presence of surface related trap sites in the PNCs, not their size distribution.…”

Section: Scheme 1 Schematic Presentation Of the Synthesis Of White-lmentioning

confidence: 99%

Pure white-light emitting ultrasmall organic–inorganic hybrid perovskite nanoclusters

et al. 2016

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Organic-inorganic hybrid perovskites, direct band-gap semiconductors have shown tremendous promise for optoelectronic device fabrication. We report the first colloidal synthetic approach to prepare ultrasmall (~1.5 nm diameter), white light emitting, organic-inorganic hybrid perovskite nanoclusters. The nearly pure white-light emitting ultrasmall nanoclusters were obtained by selectively manipulating the surface chemistry (passivating ligands and surface trap-states) and controlled substitution of halide ions. The nanoclusters displayed a combination of band-edge and broadband photoluminescence properties, covering a major part of the visible region of the solar spectrum with unprecedentedly large quantum yields of ~12% and photoluninescence lifetime of ~20 ns. The intrinsic white light emission of perovskite nanoclusters makes them ideal and low cost hybrid nanomaterials for solid-state lighting applications.The ever-increasing global demand for energy drives the need to discover highly efficient materials capable of saving energy in solid-state lighting (SSL) applications, such as light-emitting diodes (LEDs). 1,2 In this context, pure white-light emitting materials, and their subsequent uses in LED fabrication, will be a most effective way to reduce global power consumption. Currently, white-light LEDs are prepared by: (i) mixing single wavelength emitting organic phosphors, 3 and (ii) constructing multi-layer films composed of blue, green, and red color emitting semiconductor quantum dots (QDs). 4,5 However, the self-absorption process between different organic phosphors reduces device efficiency, a similar device characteristic that has also been observed for QD-based LEDs. Ultrasmall semiconductor nanoclusters (e.g., CdSe) display white-light, but they require expensive, complicated and high temperature synthetic methods. [6][7][8] Recently, white-light emitting bulk organic-inorganic perovskites were synthesized, 9,10 which would not only expand SSL research but also facilitate inexpensive LED fabrication. Scheme 1. Schematic Presentation of the Synthesis of White-Light Emitting Organolead Bromide Perovskite NanoclustersIn this communication, we report the first colloidal synthetic method to prepare white-light emitting, ultrasmall (~1.5 nm diameter) methylammonium lead bromide (MAPbBr3) perovskite nanoclusters (PNCs). Their synthesis is outlined in Scheme 1 and the detailed procedure is provided in the Electronic Supplementary Information (ESI) file. These PNCs display a combination of band-edge and broadband photoluminescence (PL) with a quantum yield (QY) of ~5% and PL lifetime of ~7 ns. We hypothesize that the broad emission properties originate from the presence of surface-related midgap trap-states. Furthermore, we showed selective manipulation of band-gap and trap-states via the preparation of mixed halide (MAPbClxBr3-x) PNCs through controlled anion exchange reactions enhanced both QY and PL lifetime at least two-fold. We believe these ultrasmall PNCs will provide fundamentally important informati...

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Section: Scheme 1 Schematic Presentation Of the Synthesis Of White-lmentioning

confidence: 99%

Pure white-light emitting ultrasmall organic–inorganic hybrid perovskite nanoclusters

et al. 2016

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“…These QDs are soluble in electrochemistry friendly solvent like acetonitrile and DCM. 72 Moreover, these two solvents allow electrochemical measurements in a larger potential window, 65 which is critical to precisely determine the ! "# !…”

Section: Size Dependent Electrochemical Properties Of Fully Diffused mentioning

confidence: 99%

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

et al. 2016

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ABSTRACT:In the past few years, there has been an immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their component. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe 2 ) NCs on visible light driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8 to 5.3 nm diameter CuInSe 2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O 2 to O 2 −) to occur at the NCs surface allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe 2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NCs size, was the dominant contributor to the overall process when compared to the contribution light absorption and the coulombic interaction energies of electronhole pair (J e/h ). A two-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe 2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe 2 NCs showed photocatalytic activity towards other organic compounds, such as N, N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light.3

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“…Кроме метода эффективной массы для определения R av часто используют выражение, полученное авторами [17], которое, несмотря на то что было получено эмпирическим путем, дает хорошие результаты. Для КТ CdS оно имеет вид [12].…”

Section: передача энергии возбуждения между кт при сильной связиunclassified

“…3 показывает большое красное смещение между ними, составляющее ∼ 100 мэВ. Величина больше этой, ∼ 170 мэВ, была получена только в массиве КТ CdTe с R < 2.5 нм [12]. Величины смещений между максимумами спектра поглощения и ФЛ пленок S1 и S2 составляют δ 1 ≈ 190 и δ 2 ≈ 280 мэВ.…”

Section: передача энергии возбуждения между кт при сильной связиunclassified

“…КТ из полупроводников II−VI, полученные в коллоидном растворе и осажденные на плоскую или выпуклую поверхность, имеют больше преимуществ перед полимерами или красителями при передаче энергии, поскольку являются химически более стабильными, а также благодаря размерному эффекту. В последнее время активно исследуются не массивы одиночных КТ, а так называемые их " строительные блоки" в связи с созданием структур с плотной упаковкой: двумерные (2D) пленки, трехмерные (3D) сверхрешетки, системы с каскадной передачей энергии (сascaded energy transfer) [2,[6][7][8][9][10][11][12]. В плотноупакованных массивах возникает сильная связь между КТ, приводящая к туннелированию квазичастиц через барьер, ширина и высота которого регулируются длиной и химической структурой связующего лиганда.…”

Section: Introductionunclassified

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Передача энергии электронного возбуждения в масcиве квантовых точек CdS на квазидвумерной поверхности

Бондарь¹,

Бродин²,

Матвеевская³

et al. 2019

Физика И Техника Полупроводников

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The optical spectra of films composed of spherical silicon-dioxide particles coated with small-radius CdS quantum dots are recorded and analyzed. Large shifts of the absorption and photoluminescence bands are detected and studied in relation to the concentration of quantum dots and to the pumping density and wavelength. Analysis of the experimental data shows that the effects are due to electronic excitation energy transfer by particles through the mechanism of tunneling induced by a strong interaction between quantum dots. The results obtained at low pumping densities and different excitation wavelengths make it possible to describe the size distribution of CdS quantum dots. This distribution can be adequately approximated with a Gaussian function.

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Solvent-like ligand-coated ultrasmall cadmium selenide nanocrystals: strong electronic coupling in a self-organized assembly

Cited by 16 publications

References 62 publications

Pure white-light emitting ultrasmall organic–inorganic hybrid perovskite nanoclusters

Pure white-light emitting ultrasmall organic–inorganic hybrid perovskite nanoclusters

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

Передача энергии электронного возбуждения в масcиве квантовых точек CdS на квазидвумерной поверхности

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