Complex diffusion-based kinetics of photoluminescence in semiconductor nanoplatelets

Kurilovich, Aleksandr A.; Манцевич, В. Н.; Stevenson, Keith J.; Chechkin, Aleksei V.; Palyulin, Vladimir V.

doi:10.1039/d0cp03744c

Cited by 30 publications

(41 citation statements)

References 60 publications

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“…Here, ω denotes the mass transfer coefficient and β = θ im /θ m the capacity coefficient often used in geophysical contexts. We highlight that this EMIM is based on the two-state, non-Markovian kinetic rate equations for exciton trapping in semiconductors developed in [65] to which we added the advection-dispersion operator.…”

Section: The Emimmentioning

confidence: 99%

“…Our model unifies the following approaches. First, it is an extension of the non-Markovian rate equations used to describe excitons in semiconductors [65] to which we add an advection-dispersion operator. A similar equation exclusively for mobile tracers without advection was presented to describe fine particle deposition in benthic biofilms [52].…”

Section: The Emimmentioning

confidence: 99%

“…To this end let us consider a general Markovian two state MIM with immobilization rate ω 1 and remobilization rate ω 2 as discussed in [65],…”

Section: A Exponential Trapping Time Distributionmentioning

confidence: 99%

“…In Section IV we show that the dynamics of the total tracer concentration in our model is a particular case of the bi-fractional diffusion equation [71], to which a transport term is added, and the fractal model [45], in the long time limit t ≫ τ ⋆ . We note that another common choice for a PDF with a power-law tail is the one-sided Lévy distribution [34,65,71]. While the latter is supported formally by the generalized central limit theorem [85], its more intricate Laplace transform exp(−(τ ⋆ s) µ ) renders analytical calculations virtually impossible.…”

Section: B Mittag-leffler Trapping Time Distributionmentioning

confidence: 99%

“…Dye or fine particles are injected into the mobile zone of a groundwater system or river. In our extended mobile-immobile model (EMIM), which is based on [65,66], the tracers immobilize in dead-end pores, the hyporheic zone, or biofilms for a random time τ drawn from a probability density γ(τ ); see Eq. ( 1) for details.…”

Section: Introductionmentioning

confidence: 99%

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Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions

Doerries,

Chechkin,

Schumer

et al. 2022

Preprint

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We present a framework for systems in which diffusion-advection transport of a tracer substance in a mobile zone is interrupted by trapping in an immobile zone. Our model unifies different model approaches based on distributed-order diffusion equations, exciton diffusion rate models, and random walk models for multi-rate mobile-immobile mass transport. We study various forms for the trapping time dynamics and their effects on the tracer mass in the mobile zone. Moreover we find the associated breakthrough curves, the tracer density at a fixed point in space as function of time, as well as the mobile and immobile concentration profiles and the respective moments of the transport. Specifically we derive explicit forms for the anomalous transport dynamics and an asymptotic power-law decay of the mobile mass for a Mittag-Leffler trapping time distribution. In our analysis we point out that even for exponential trapping time densities transient anomalous transport is observed. Our results have direct applications in geophysical contexts but also in biological, soft matter, and solid state systems.

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Section: The Emimmentioning

confidence: 99%

Section: The Emimmentioning

confidence: 99%

“…To this end let us consider a general Markovian two state MIM with immobilization rate ω 1 and remobilization rate ω 2 as discussed in [65],…”

Section: A Exponential Trapping Time Distributionmentioning

confidence: 99%

Section: B Mittag-leffler Trapping Time Distributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions

Doerries,

Chechkin,

Schumer

et al. 2022

Preprint

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Dark‐Bright Exciton Splitting Dominates Low‐Temperature Diffusion in Halide Perovskite Nanocrystal Assemblies

Bornschlegl,

Lichtenegger,

Luber

et al. 2024

Advanced Energy Materials

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Semiconductor nanocrystals can replace conventional bulk materials completely in displays and light‐emitting diodes. Exciton transport dominates over charge carrier transport for materials with high exciton binding energies and long ligands, such as halide perovskite nanocrystal films. Here, how beneficial superlattices – nearly perfect 3D assemblies of nanocrystals ‐ are to exciton transport is investigated. Surprisingly, the high degree of order is not as crucial as the individual nanocrystal size, which strongly influences the splitting of the excitonic manifold into bright and dark states. At very low temperatures, the energetic splitting is larger for the smallest nanocrystals, and dark levels with low oscillator strength effectively trap excitons inside individual nanocrystals, suppressing diffusion. The effect is reversed at elevated temperatures, and the larger nanocrystal size becomes detrimental to exciton transport due to enhanced exciton trapping and dissociation. The results reveal that the nanocrystal size must be strongly accounted for in design strategies of future optoelectronic applications.

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Fine‐Tuning Crystal Structures of Lead Bromide Perovskite Nanocrystals through Trace Cadmium(II) Doping for Efficient Color‐Saturated Green LEDs

Zhang,

Wang,

Cai

et al. 2024

Angewandte Chemie

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Decreasing perovskite nanocrystal size increases radiative recombination due to the quantum confinement effect, but also increases the Auger recombination rate which leads to carrier imbalance in the emitting layers of electroluminescent devices. Here, we overcome this trade‐off by increasing the exciton effective mass without affecting the size, which is realized through the trace Cd2+ doping of formamidinium lead bromide perovskite nanocrystals. We observe an ~2.7 times increase in the exciton binding energy benefiting from a slight distortion of the [BX6]4− octahedra caused by doping in the case of that the Auger recombination rate is almost unchanged. As a result, bright color‐saturated green emitting perovskite nanocrystals with a photoluminescence quantum yield of 96% are obtained. The light‐emitting devices based on those nanocrystals reached a high external quantum efficiency (EQE) of 29.4% corresponding to a current efficiency of 123 cd A‐1, and showed dramatically improved device lifetime, with a narrow bandwidth of 22 nm and Commission Internationale de I’Eclairage coordinates of (0.20, 0.76) for color‐saturated green emission for the electroluminescence peak centered at 534 nm, thus being fully compliant with the latest standard for wide color gamut displays.

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Complex diffusion-based kinetics of photoluminescence in semiconductor nanoplatelets

Abstract: We present a diffusion-based simulation and theoretical models for explanation of photoluminescence (PL) emission intensity in semiconductor nanoplatelets. It is shown that the shape of PL intensity curves can be...

Cited by 30 publications

References 60 publications

Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions

Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions

Dark‐Bright Exciton Splitting Dominates Low‐Temperature Diffusion in Halide Perovskite Nanocrystal Assemblies

Fine‐Tuning Crystal Structures of Lead Bromide Perovskite Nanocrystals through Trace Cadmium(II) Doping for Efficient Color‐Saturated Green LEDs

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