Long-Lived and Bright Biexcitons in Quantum Dots with Parabolic Band Potentials

Diroll, Benjamin T.; Hua, Muchuan; Guzelturk, Burak; Pálmai, Marcell; Tomczak, Kyle

doi:10.1021/acs.nanolett.3c04361

Cited by 6 publications

(3 citation statements)

References 56 publications

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“…The core/shell quantum dot shows a much smaller LY, around 1000 ph MeV −1 , consistent with prior reports 9 . Our LY characterization method also showed a much smaller LY (6,700 ph MeV −1 ) when measuring a core/gradient-shell quantum dot structure 31 . This indicates that the QSs show a substantial improvement in scintillation efficiency.…”

Section: Resultsmentioning

confidence: 84%

Bright and durable scintillation from colloidal quantum shells

Guzelturk,

Diroll,

Cassidy

et al. 2024

Nat Commun

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Efficient, fast, and robust scintillators for ionizing radiation detection are crucial in various fields, including medical diagnostics, defense, and particle physics. However, traditional scintillator technologies face challenges in simultaneously achieving optimal performance and high-speed operation. Herein we introduce colloidal quantum shell heterostructures as X-ray and electron scintillators, combining efficiency, speed, and durability. Quantum shells exhibit light yields up to 70,000 photons MeV−1 at room temperature, enabled by their high multiexciton radiative efficiency thanks to long Auger-Meitner lifetimes (>10 ns). Radioluminescence is fast, with lifetimes of 2.5 ns and sub-100 ps rise times. Additionally, quantum shells do not exhibit afterglow and maintain stable scintillation even under high X-ray doses (>109 Gy). Furthermore, we showcase quantum shells for X-ray imaging achieving a spatial resolution as high as 28 line pairs per millimeter. Overall, efficient, fast, and durable scintillation make quantum shells appealing in applications ranging from ultrafast radiation detection to high-resolution imaging.

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Section: Resultsmentioning

confidence: 84%

Bright and durable scintillation from colloidal quantum shells

Guzelturk,

Diroll,

Cassidy

et al. 2024

Nat Commun

Self Cite

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“…This geometric separation of charge carriers results in multiexciton formation that is advantageous for lasing and can affect the single-photon purity. 32,[35][36][37][38] The two main methods to grow large core/shell CdSe/CdS are successive ionic layer adsorption and reaction (SILAR) and high-temperature continuous injection (HTCI). 29,30,39 The differences between the two methods and the correlation between synthetic conditions and QD properties have been rigorously studied by Hollingsworth and coworkers.…”

Section: Introductionmentioning

confidence: 99%

Colossal Core/Shell CdSe/CdS Quantum Dot Emitters

Nguyen,

Hammel,

Sharp

et al. 2024

Preprint

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Single-photon sources are essential for advancing quantum technologies, with scalable integration being a crucial requirement. To date, deterministic positioning of single-photon sources in large-scale photonic structures remains a challenge. In this context, colloidal quantum dots (QDs), particularly core/shell configurations, are attractive due to their solution processability. However, traditional QDs are typically small, about 3 to 6 nm, which restricts their deterministic placement and utility in large-scale photonic devices. The largest existing core/shell QDs are the family of giant CdSe/CdS QDs, with total diameters ranging from about 20 to 50 nm. Pushing beyond this size limit, we introduce a synthesis strategy for colossal CdSe/CdS QDs, with sizes ranging from 30 to 100 nm, using a stepwise high-temperature continuous injection method. Electron microscopy reveals a consistent hexagonal diamond morphology composed of twelve semipolar {101 ̅1} facets and one polar (0001) facet. We also identify conditions where shell growth is disrupted, leading to defects, islands, and mechanical instability, which suggest synthetic requirements for growing crystalline particles beyond 100 nm. The stepwise growth of thick CdS shells on CdSe cores enables the synthesis of emissive QDs with long photoluminescence lifetimes of a few microseconds and suppressed blinking at room temperature. Notably, QDs with 100 CdS monolayers exhibit high single-photon emission purity with second-order photon correlation g(2)(0) values below 0.2. Our findings indicate that colossal core/shell QDs can efficiently emit single photons, which paves the way for quantum photonic applications that require deterministic placement of single-photon sources.

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“…The largest emissive QDs without silica shells reported in the literature to date are the traditional quasi-type II giant core/shell CdSe/CdS QDs, with 15–20 CdS monolayers (MLs) and total diameters ranging from 20 to 50 nm. − The giant CdS shells not only increase the size of the emissive QDs but also reduce blinking through Auger recombination suppression and isolate the exciton from surface interactions. ,, In these quasi-type II core/shell systems, the electron wave function is delocalized into the CdS shell, while the hole wave function is effectively confined within the CdSe core. This geometric separation of charge carriers results in multiexciton formation that is advantageous for lasing and can affect the single-photon purity. ,− …”

Section: Introductionmentioning

confidence: 99%

Colossal Core/Shell CdSe/CdS Quantum Dot Emitters

Nguyen,

Hammel,

Sharp

et al. 2024

ACS Nano

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Single-photon sources are essential for advancing quantum technologies with scalable integration being a crucial requirement. To date, deterministic positioning of singlephoton sources in large-scale photonic structures remains a challenge. In this context, colloidal quantum dots (QDs), particularly core/shell configurations, are attractive due to their solution processability. However, traditional QDs are typically small, about 3 to 6 nm, which restricts their deterministic placement and utility in large-scale photonic devices, particularly within optical cavities. The largest existing core/shell QDs are a family of giant CdSe/CdS QDs, with total diameters ranging from about 20 to 50 nm. Pushing beyond this size limit, we introduce a synthesis strategy for colossal CdSe/CdS QDs, with sizes ranging from 30 to 100 nm, using a stepwise high-temperature continuous injection method. Electron microscopy reveals a consistent hexagonal diamond morphology composed of 12 semipolar {101̅ 1} facets and one polar (0001) facet. We also identify conditions where shell growth is disrupted, leading to defects, islands, and mechanical instability, which suggest synthetic requirements for growing crystalline particles beyond 100 nm. The stepwise growth of thick CdS shells on CdSe cores enables the synthesis of emissive QDs with long photoluminescence lifetimes of a few microseconds and suppressed blinking at room temperature. Notably, QDs with 80 and 100 CdS monolayers exhibit high single-photon emission purity with second-order photon correlation g (2) (0) values below 0.2.

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Long-Lived and Bright Biexcitons in Quantum Dots with Parabolic Band Potentials

Cited by 6 publications

References 56 publications

Bright and durable scintillation from colloidal quantum shells

Bright and durable scintillation from colloidal quantum shells

Colossal Core/Shell CdSe/CdS Quantum Dot Emitters

Colossal Core/Shell CdSe/CdS Quantum Dot Emitters

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