Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots

Freymeyer, Nathaniel J.; Click, Sophia M; Reid, Kemar R.; Chisholm, Matthew F.; Bradsher, Cara E.; McBride, James R.; Rosenthal, Sandra J.

doi:10.1063/1.5145189

Cited by 21 publications

(22 citation statements)

References 51 publications

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“…Electronic transitions (B) that give rise to the features in the optical absorption spectra of CdSe nanocrystals, reproduced with permission from Klimov et al (Klimov et al, 1999a). (C) Band structure of CdSe nanocrystals (C) illustrating the quantization of states at the band edge and mid-gap states that can arise from surface states and/or alloying (Freymeyer et al, 2020;Underwood et al, 2001b). Illustration developed from theoretical results of Ekimov, Efros, et al (Ekimov et al, 1993).…”

Section: Ll Open Accessmentioning

confidence: 99%

“…( Klimov et al., 1999a ). (C) Band structure of CdSe nanocrystals (C) illustrating the quantization of states at the band edge and mid-gap states that can arise from surface states and/or alloying ( Freymeyer et al., 2020 ; Underwood et al., 2001b ). Illustration developed from theoretical results of Ekimov, Efros, et al.…”

Section: Semiconductor Nanocrystalsmentioning

confidence: 99%

“…Additional study of InP core-based nanocrystals includes recent work by Rosenthal et al. who studied thick-shell InP/ZnSe core/shell nanocrystals and compared an abrupt core/shell interface to an alloyed interface ( Freymeyer et al., 2020 ). Using both fluorescence upconversion and TCSPC, both samples exhibit sub-200 fs carrier cooling, ∼6 ps hole trapping, ∼26–37 ps electron trapping, and ∼16–18 ns long-lived radiative recombination.…”

Section: Carrier Dynamics In Nontraditional/nonbinary Nanocrystalline...mentioning

confidence: 99%

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Ultrafast spectroscopy studies of carrier dynamics in semiconductor nanocrystals

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Section: Ll Open Accessmentioning

confidence: 99%

Section: Semiconductor Nanocrystalsmentioning

confidence: 99%

Section: Carrier Dynamics In Nontraditional/nonbinary Nanocrystalline...mentioning

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Ultrafast spectroscopy studies of carrier dynamics in semiconductor nanocrystals

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“…Developing eco-friendly, low-toxic or non-toxic QD materials is key to solving the above problems [14]. Indium phosphide (InP)-based QDs have attracted wide attention from researchers because of their high fluorescence quantum yield, low toxicity, and environment friendliness [15][16][17], and are considered a candidate to replace Cd-based QDs [18]. Generally, a multi-layer device structure that includes an electron injection/transport layer (EIL/ETL), emitting layer (EML), hole injection/transport layer (HIL/HTL), and electrode layer is required to achieve high-performance InP-based QLED, which helps to balance the injection of carriers and reduce the barrier of interface [1,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Effects of ZnMgO Electron Transport Layer on the Performance of InP-Based Inverted Quantum Dot Light-Emitting Diodes

et al. 2021

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An environment-friendly inverted indium phosphide red quantum dot light-emitting diode (InP QLED) was fabricated using Mg-doped zinc oxide (ZnMgO) as the electron transport layer (ETL). The effects of ZnMgO ETL on the performance of InP QLED were investigated. X-ray diffraction (XRD) analysis indicated that ZnMgO film has an amorphous structure, which is similar to zinc oxide (ZnO) film. Comparison of morphology between ZnO film and ZnMgO film demonstrated that Mg-doped ZnO film remains a high-quality surface (root mean square roughness: 0.86 nm) as smooth as ZnO film. The optical band gap and ultraviolet photoelectron spectroscopy (UPS) analysis revealed that the conduction band of ZnO shifts to a more matched position with InP quantum dot after Mg-doping, resulting in the decrease in turn-on voltage from 2.51 to 2.32 V. In addition, the ratio of irradiation recombination of QLED increases from 7% to 25% using ZnMgO ETL, which can be attributed to reduction in trap state by introducing Mg ions into ZnO lattices. As a result, ZnMgO is a promising material to enhance the performance of inverted InP QLED. This work suggests that ZnMgO has the potential to improve the performance of QLED, which consists of the ITO/ETL/InP QDs/TCTA/MoO3/Al, and Mg-doping strategy is an efficient route to directionally regulate ZnO conduction bands.

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“…27,28 The achievement of 100% photoluminescence quantum yield (PL QY) has been attributed to well-confined electron and hole wavefunctions through engineering the inner shell layer, 25,29 removal of oxidative defects by etching with HF prior to shelling, 7 a well-passivated surface on a stoichiometric InP core, 8 and removal of indium defects in the shell by an additional washing step. 8,30 The high sensitivity of optical properties to the core stoichiometry and interface morphology has been highlighted in recent computational studies. 31,32 These considerations are influenced by the composition and the chemical environment at the core/shell interface, highlighting the need for further investigation on the nature of surface trap states and how to deterministically treat the quantum dot core en route to highly emissive, defect-free core/shell QDs.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Interfacial Stoichiometry of InP Core and InP/ZnSe Core/Shell Quantum Dots

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Eagle

DeLarme

et al. 2021

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We demonstrate fine-tuning of the atomic composition of InP/ZnSe QDs at the core/shell interface. Specifically, we control the stoichiometry of both anions (P, As, S, and Se) and cations (In, Zn) at the InP/ZnSe core/shell interface and correlate these changes with the resultant steadystate and time-resolved optical properties of the nanocrystals. The use of reactive trimethylsilyl reagents results in surface-limited reactions that shift the nanocrystal stoichiometry to anion-rich and improve epitaxial growth of the shell layer. In general, anion deposition on the InP QD surface results in a redshift in the absorption, quenching of the excitonic photoluminescence, and a relative increase in the intensity of the broad trap-based photoluminescence, consistent with delocalization of the exciton wavefunction and relaxation of exciton confinement. Time-resolved photoluminescence data for the resulting InP/ZnSe QDs show an overall small change in the decay dynamics on the ns timescale, suggesting the relatively low photoluminescence quantum yields may be attributed to the creation of new thermally activated charge trap states and likely a dark population that is inseparable from the emissive QDs. Cluster-model density functional theory calculations show that the presence of core/shell interface anions give rise to electronic defects contributing to the redshift in the absorption. These results highlight a general strategy to atomistically tune the interfacial stoichiometry of InP QDs using surface-limited reaction chemistry allowing for precise correlations with electronic structure and photophysical processes.

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Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots

Cited by 21 publications

References 51 publications

Ultrafast spectroscopy studies of carrier dynamics in semiconductor nanocrystals

Ultrafast spectroscopy studies of carrier dynamics in semiconductor nanocrystals

Effects of ZnMgO Electron Transport Layer on the Performance of InP-Based Inverted Quantum Dot Light-Emitting Diodes

Tuning the Interfacial Stoichiometry of InP Core and InP/ZnSe Core/Shell Quantum Dots

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