Size- and Temperature-Dependent Carrier Dynamics in Oleic Acid Capped PbS Quantum Dots

Andreakou, P.; Brossard, M.; Li, Chunyong; Bernechea, María; Konstantatos, Gerasimos; Lagoudakis, Pavlos G.

doi:10.1021/jp3054108

Cited by 38 publications

(22 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It should be emphasized that τ i remain almost constant at first but then evolve with different behaviors at temperatures over ∼180 K, where τ 1 and τ 2 decrease while the slowest τ 3 increases. This represents a temperature-induced transfer of carriers/excitons from the state related to τ 1 or τ 2 to the state of τ 3 (increasing the exciton concentration of the τ 3 state) [25]. This is again in full agreement with a relaxation mechanism as proposed in Fig.…”

supporting

confidence: 86%

Experimental observation of exciton splitting and relaxation dynamics from PbS quantum dots in a glass matrix

2014

View full text Add to dashboard Cite

Multiple optical transitions from PbS quantum dots (QDs) in glass matrix are observed. Energy separations between them amount up to ∼200 meV. Instead of being due to a size distribution of QDs, they are found to be related to a splitting of the lowest exciton levels. Systematic analysis of the relaxation dynamics reveals the lifetimes of the split states ranging from sub-100-ns to ∼μs. Moreover, we observe excited and "intrinsic" states having a sub-100-ps and ∼ns lifetime, respectively. The behavior of the split structure can be modeled by a phonon-assisted relaxation mechanism. This investigation offers a conclusive interpretation for the wide distribution of experimentally observed nonequilibrium carrier lifetimes in PbS QDs.Lead salt (e.g., PbS) quantum dots (QDs) have been widely investigated for applications in optoelectronic devices [1,2]. The QDs are either colloidal or embedded into a glass matrix. The latter provides substantial advantages in terms of longterm stability [3]. In order to evaluate and improve the properties of materials or devices, the QD size and its distribution as well as the excitonic lifetime are major issues, which should be accurately characterized, e.g., directly by optical methods including steady-state (SS) or transient absorption and photoluminescence (PL) spectroscopy at room temperature [4].However, in rock salt PbS QDs the dimension of the excitonic manifold is theoretically 64 because both the valence-band maximum and the conduction-band minimum originate from the 8-fold (including spin) L valleys in the first Brillouin zone of bulk PbS. The degeneracy of these L valleys becomes lifted due to, e.g., intervalley coupling, interband coupling, and electron-hole Coulomb and exchange interaction [5]. Another mechanism potentially acting into this direction is external forces such as pressure as well as a special chemical surrounding, e.g., in a matrix. The split structure makes the optical transition in QDs complex and affects the characterization of QD features including the lowest excitonic transition energy (for simplicity called E g ) and subsequently the size and distribution of QDs as well as the nonequilibrium carrier recombination mechanism. In spite of the fact that asymmetric-or multi-PL (or absorption) peaks from these kinds of QDs have been observed even at room temperature, no direct reports involve these split states. Typically extrinsic assumptions are made including size distribution (e.g., multimodal QDs) [6], temperature/excitation-induced broadening [7], or defect states [8,9].In this Rapid Communication, PbS QDs embedded in a borosilicate glass matrix are prepared and characterized by SS-or transient-PL spectroscopy at low excitation densities and temperatures. A three-transition structure from the QDs is observed with an energy separation up to 200 meV, in dependence of growth conditions including annealing. The * yue@mbi-berlin.de intrinsic mechanism for this three-transition structure that seems to be sensitive to the host matrix, e.g., with borosilicate b...

show abstract

supporting

confidence: 86%

Experimental observation of exciton splitting and relaxation dynamics from PbS quantum dots in a glass matrix

2014

View full text Add to dashboard Cite

show abstract

“…The observed trend has been extensively explained in ref. [17], where it was shown that the radiative decay rate of bright excitons is around two orders of magnitude larger than the rate of dark excitons. It is therefore understood that in the framework of RET the bright excitons dominate the dynamics.…”

Section: -Results and Discussionmentioning

confidence: 99%

Spectroscopic evidence of resonance energy transfer mechanism from PbS QDs to bulk silicon

Andreakou

Brossard

et al. 2013

EPJ Web of Conferences

View full text Add to dashboard Cite

Summary. -In this work, we study the efficiency of the resonance energy transfer from PbS quantum dots to bulk silicon. We present spectroscopic evidence that resonance energy transfer from PbS quantum dots to bulk silicon can be an efficient process for separation distances below 12 nm. Temperature measurements are also presented for PbS quantum dots deposited on glass and silicon with 5 nm and 20 nm spacer thicknesses substrates. Our findings show that the resonance energy transfer efficiency remains constant over the 50 K to 300 K temperature range.

show abstract

“…Управление характеристиками размернозависимой ИК люминесценции КТ Ag 2 S практически важно в силу их низких водорастворимости и токсичности [7][8][9][10][11]. Существенная нестехиометрия сульфида серебра и его фотохимическая активность оказывают нежелательное воздействие на квантовый выход (QY) люминесценции, и даже приводят к заметной деградации его люминесцентных свойств под действием возбуждающего излучения [12][13][14][15][16][17][18][19]. Поскольку рекомбинационная люминесценция КТ Ag 2 S имеет интерфейсную природу [20,21], формирование структур ядро/оболочка на их основе является эффективным способом повышения QY.…”

Section: Introductionunclassified

Квантовый выход люминесценции и константы рекомбинации в коллоидных core/shell квантовых точках Ag-=SUB=-2-=/SUB=-S/AnS и Ag-=SUB=-2-=/SUB=-S/SiO-=SUB=-2-=/SUB=-

Ovchinnikov¹,

Aslanov²

2020

Журнал Технической Физики

View full text Add to dashboard Cite

Выполнен сравнительный анализ люминесцентных свойств коллоидных квантовых точек Ag2S, покрытых тиогликолевой кислотой или 2-меркаптопропионовой кислотой c оболочками из ZnS или SiO2. Продемонстрировано увеличение квантового выхода рекомбинационной ИК люминесценции коллоидных квантовых точек Ag2S до 35 раз в результате формирования оболочек ZnS, SiO2 при одновременном увеличении среднего времени жизни люминесценции. Для квантовых ядро/оболочка Ag2S/ZnS покрытых тиогликолевой кислотой показано уменьшение излучательной и безызлучательной констант рекомбинации, которое объяснено локализацией электронов в оболочке, а дырок в ядре. Для квантовых точек ядро/оболочка Ag2S/SiO2 покрытых 2-меркаптопропионовой кислотой наблюдалось увеличение констант излучательной и уменьшение безызлучательной рекомбинации. В этом случае рост константы излучательной рекомбинации обусловлен локализацией электронов и дырок в ядре. Уменьшение константы безызлучательной рекомбинации объяснено пассивацией интерфейсных дефектов квантовых точек при формировании оболочки. Ключевые слова: квантовые точки, люминесценция, константы рекомбинации, core/shell.

show abstract

Size- and Temperature-Dependent Carrier Dynamics in Oleic Acid Capped PbS Quantum Dots

Cited by 38 publications

References 34 publications

Experimental observation of exciton splitting and relaxation dynamics from PbS quantum dots in a glass matrix

Experimental observation of exciton splitting and relaxation dynamics from PbS quantum dots in a glass matrix

Spectroscopic evidence of resonance energy transfer mechanism from PbS QDs to bulk silicon

Квантовый выход люминесценции и константы рекомбинации в коллоидных core/shell квантовых точках Ag-=SUB=-2-=/SUB=-S/AnS и Ag-=SUB=-2-=/SUB=-S/SiO-=SUB=-2-=/SUB=-

Contact Info

Product

Resources

About