The role of mid-gap states in all-inorganic CsPbBr<sub>3</sub> nanoparticle one photon up-conversion

Roman, Benjamin J.; Sheldon, Matthew

doi:10.1039/c8cc02430h

Cited by 27 publications

(51 citation statements)

References 23 publications

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“…The converse process, in which a material emits higher energy light than it absorbs, is commonly known as luminescence up-conversion [1,2]. While the majority of research into luminescence up-conversion is focused on nonlinear, multi-photon excitation mechanisms, there are material systems for which one-photon up-conversion, also called anti-Stokes photoluminescence (ASPL), is possible [3][4][5][6][7][8][9][10][11]. As the name implies, ASPL is the reverse process of the thermalization loss that gives rise to Stokes-shifted PL.…”

Section: Introductionmentioning

confidence: 99%

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Roman

Sheldon

2019

Nanophotonics

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One-photon up-conversion, also called anti-Stokes photoluminescence (ASPL), is the process whereby photoexcited carriers scavenge thermal energy and are promoted into a higher energy excited state before emitting a photon of greater energy than initially absorbed. Here, we examine how ASPL from CsPbBr3 nanoparticles is modified by coupling with plasmonically active gold nanoparticles deposited on a substrate. Two coupling regimes are examined using confocal fluorescence microscopy: three to four Au nanoparticles per diffraction limited region and monolayer Au nanoparticle coverage of the substrate. In both regimes, CsPbBr3 ASPL is blue-shifted relative to CsPbBr3 deposited on a bare substrate, corresponding to an increase in the thermal energy scavenged per emitted photon. However, with monolayer Au nanoparticle coverage, ASPL is enhanced relative to the conventional Stokes-shifted PL. Together, these phenomena result in a 6.7-fold increase in the amount of thermal energy extracted from the system during optical absorption and reemission.

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Section: Introductionmentioning

confidence: 99%

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Roman

Sheldon

2019

Nanophotonics

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“…This entails observations of redshifted ASPL spectra relative to the normal NC/nanostructure band edge emission. These redshifts have been observed in CdS 1 − x Se x 110 , CdSe 59,62,109 , CdTe 59,63,65,66,71,105,112,113 , PbS NC-doped glasses 67,115 , CsPbBr 3 73,103 , and CsPbBrI 2 NCs 69 . Figure 9a provides an example, showing the apparent~8 meV redshift between the emission and ASPL spectra of a CsPbBr 3 NC ensemble.…”

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confidence: 74%

“…Lowering NC/nanostructure trap densities should therefore increase I ASPL . This last prediction is important because it has been observed that I ASPL increases with increasing QYs in both CdSe 60,61 and CsPbBr 3 NCs 73 . We also observe this behavior in CdSe/ CdS NCs studied here.…”

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confidence: 87%

“…A few suggest the involvement of virtual intermediate states, especially when two-photon upconversion has been claimed (e.g., in CdS 70 and CdTe 71 NCs). Others (e.g., PbS 72 and CsPbBr 3 73 ) leave open the possibility of another upconversion mechanism, as of yet undefined. Figure 2 schematically illustrates one-photon processes involving virtual ( Fig.…”

Section: Towards Nanostructuresmentioning

confidence: 99%

“…, CdS 56 , CdSe [58][59][60][61][62]104 , CdTe 59,[63][64][65]105 , PbS 67 , CsPbBr 3 73,103 , and CsPbBrI 2 69,106 . Other nanostructures exhibiting linear I ASPL versus I exc behavior include CdS NBs 47,57,107 , ZnTe nanoribbons 108 , bulk MAPbI 3…”

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confidence: 99%

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Progress in laser cooling semiconductor nanocrystals and nanostructures

et al. 2019

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Over the past two decades, there have been sizable efforts to realize condensed phase optical cooling. To date, however, there have been no verifiable demonstrations of semiconductor-based laser cooling. Recently, advances in the synthesis of semiconductor nanostructures have led to the availability of high-quality semiconductor nanocrystals, which possess superior optical properties relative to their bulk counterparts. In this review, we describe how these nanostructures can be used to demonstrate condensed phase laser cooling. We begin with a description of charge carrier dynamics in semiconductor nanocrystals and nanostructures under both above gap and below-gap excitation. Two critical parameters for realizing laser cooling are identified: emission quantum yield and upconversion efficiency. We report the literature values of these two parameters for different nanocrystal/nanostructure systems as well as the measurement approaches used to estimate them. We identify CsPbBr 3 nanocrystals as a potential system by which to demonstrate verifiable laser cooling given their ease of synthesis, near-unity emission quantum yields and sizable upconversion efficiencies. Feasibility is further demonstrated through numerical simulations of CsPbBr 3 nanocrystals embedded in an aerogel matrix. Our survey generally reveals that optimized semiconductor nanocrystals and nanostructures are poised to demonstrate condensed phase laser cooling in the near future.

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Two‐Step Anti‐Stokes Photoluminescence of CsPbX₃ Nanocrystals

Zhang

Liu

et al. 2020

Advanced Optical Materials

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Cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (NCs) exhibit efficient anti‐Stokes photoluminescence (ASPL) upon sub‐gap single‐photon excitation, which has great potential for all‐solid‐state laser cooling. However, the mechanism responsible for the ASPL still remains elusive. Here, ASPL properties of CsPb(BrI)3 NCs and CsPbI3 NCs in inorganic solid matrix are investigated. Excitation wavelength‐ and power‐dependent ASPL demonstrates that it is a phonon‐assisted single‐photon process. Femtosecond transient absorption spectra show that ASPL is mediated by the Urbach tail states, where localized excitons are generated upon sub‐gap excitation. Through electron–phonon coupling, these localized excitons change into free exciton to generate the exciton bleaching, and then thermally dissociate into free carriers accompanied by band edge bleaching, leading to the efficient ASPL. Such a two‐step up‐conversion process is further confirmed by the carrier temperature extracted from the band edge bleaching band. This work deepens the understanding of ASPL in CsPbX3 NCs, and is valuable for the development of materials for solid‐state laser cooling.

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The role of mid-gap states in all-inorganic CsPbBr₃ nanoparticle one photon up-conversion

Cited by 27 publications

References 23 publications

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Progress in laser cooling semiconductor nanocrystals and nanostructures

Two‐Step Anti‐Stokes Photoluminescence of CsPbX₃ Nanocrystals

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The role of mid-gap states in all-inorganic CsPbBr3 nanoparticle one photon up-conversion

Cited by 27 publications

References 23 publications

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr3 anti-Stokes photoluminescence

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr3 anti-Stokes photoluminescence

Progress in laser cooling semiconductor nanocrystals and nanostructures

Two‐Step Anti‐Stokes Photoluminescence of CsPbX3 Nanocrystals

Contact Info

Product

Resources

About

The role of mid-gap states in all-inorganic CsPbBr₃ nanoparticle one photon up-conversion

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Six-fold plasmonic enhancement of thermal scavenging via CsPbBr₃ anti-Stokes photoluminescence

Two‐Step Anti‐Stokes Photoluminescence of CsPbX₃ Nanocrystals