Unconventional gap state of trapped exciton in lead sulfide quantum dots

Lewis, Jason; Wu, Shuxiang; Jiang, Xiran

doi:10.1088/0957-4484/21/45/455402

Cited by 43 publications

(91 citation statements)

References 53 publications

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“…Recently, we have applied this method to PbS and PbSe quantum dots system [23,24,34]. This methodology is very useful to study long-lived, ingap states and their associated photoexcitations.…”

Section: Experimental Methodologymentioning

confidence: 99%

“…We also rule out G.S to be a dark exciton state in PbS quantum dots, since the gap state is too 'deep' for dark exciton state from exchange splitting, which was calculated to be less than 10 meV below the lowest bright exciton for a 4.2 nm PbS QD [18], on the other hand, the activation energy of G.S was measured to be about 20 meV [24]. In terms of Stokes shift, even counting the total splitting due to exchange and intervalley interactions, the calculated value was less than 80 meV, whereas the Stokes shift we measured is 332 meV for this size QD [24]. These inconsistencies mean that G.S.…”

Section: Spectral Signature Of Neutral Speciesmentioning

confidence: 99%

“…A detailed analysis of temperature dependence of photoluminescence (PL), absorption and photoinduced absorption (PA) reveals the unconventional G.S. is a new state of trapped exciton in QD film [24]. The importance of such gap state is illustrated below through the analysis of exciton loss mechanisms in QDs.…”

Section: Introductionmentioning

confidence: 98%

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In-Gap State of Lead Chalcogenides Quantum Dots

Jiang¹

2012

Fingerprints in the Optical and Transport Properties of Quantum Dots

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Section: Experimental Methodologymentioning

confidence: 99%

Section: Spectral Signature Of Neutral Speciesmentioning

confidence: 99%

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In-Gap State of Lead Chalcogenides Quantum Dots

Jiang¹

2012

Fingerprints in the Optical and Transport Properties of Quantum Dots

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“…Recently, temperature dependent absorption and photoluminescence (PL) of lead sulphide nanocrystals (PbS-NCs) were presented by Lewis et al [1] showing the well known redshift as temperature is reduced. This behaviour is in contrast to most semiconductors which instead display a blueshift with reducing temperature.…”

mentioning

confidence: 99%

“…(1) Figure 3(a) in [1] provides the required data for such analysis which the authors present in figure 4(a). However, as can be clearly seen from figure 3(a) (E should be negative leading to d?E/dT being positive as opposed to that presented in Figure 4(a).…”

mentioning

confidence: 99%

Comment on ‘Unconventional gap state of trapped exciton in lead sulfide quantum dots’

Curry¹

2011

Nanotechnology

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In a recent paper Lewis et al (2010 Nanotechnology 21 45502) proposed a previously unidentified gap state within lead sulphide nanocrystals (PbS-NCs) based on analysis of their temperature dependent optical properties. In the following we argue that due to oversights in the analysis of the data presented, inconsistencies arise which question their exclusion of 'dark' excitonic states as the origin of the observed effects.

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Strong Enhancement of PbS Quantum Dot NIR Emission Using Plasmonic Semiconductor Nanocrystals in Nanoporous Silicate Matrix

Litvin

Babaev

Dubavik

et al. 2018

Advanced Optical Materials

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quantum yields (PLQY), and wide tunability, combined with low material costs. [10,11] In which case the identification of an appropriate metal NIR plasmonic nanostructure is the next challenge, with only some complex gold nanostructures, such as tetrapods, [12] nanorods, [13] nanocages, [14] nanostars, [15] and faceted gold nanoparticles [16] can be cited. However, their plasmonic resonance bands are still limited in their tunable range to no longer than 1.0 µm and in addition their commercial manufacturing is highly costly. More recently, semiconductor nanocrystals with plasmonic features have attracted much attention, [17][18][19][20] with one particular example, copper deficient copper chalcogenides, [21][22][23][24][25][26][27] offering tunable plasmonic bands covering a wide range of the NIR. Plasmonic resonance in such semiconductor plasmonic nanocrystals (PNCs) arises from the excess of free holes and can be easily and reversibly tuned throughout the entire NIR spectral range. Although it is expected that near-field enhancement of optical responses by such PNCs will be less effective as compared to the noble metals in the visible range due to the smaller number of free carriers, [18] there are a few encouraging reports for PNC enhanced Raman scattering [28] and upconversion visible emission. [29] Despite the huge potential of plasmonic enhancement of NIR optical responses, especially NIR absorption and photoluminescence (PL), this topic has not been studied as of yet, with copper chalcogenides PNCs considered mostly for thermal therapy. [18,20] To realize a miniature NIR emitter which exploits plasmonic enhancement of radiation, an appropriate matrix must be selected. Such a matrix must provide optical transparency and high loading of nanoscale emitters. Importantly, the emitters and PNCs should be separated from each other to prevent PL quenching by means of nonradiative energy transfer. [1,30] At the same time, the distance between the emitter and PNC should be short enough (≈5-20 nm) to provide an effective enhancement. [1] The nanoporous silicate matrix (NSM) can satisfy these demands. [31,32] Its porous structure provides the separation between embedded QDs and PNCs, while high porosity allows the high loading of the nanoparticles.Nowadays PbS QDs are considered as a promising material for NIR photovoltaic and light-emitting devices. [33][34][35][36][37] However, the efficiency of the PbS QD light emitters is still far behind that for visible QDLEDs. [38,39] Here we report high (up to ≈20 times Strong enhancement of near-infrared (NIR) emission of lead sulfide quantum dots (QDs) induced by Cu 2−x Se semiconductor plasmonic nanocrystals (PNCs), both embedded into nanoporous silicate matrix is reported. The emission enhancement comes from resonant interaction of QD optical transition dipole with the near field of plasmons of semiconductor PNCs. Possible mechanisms of QD photoluminescence broadening and shift, including Rabi splitting and trap-state-related photoluminescence enhancement, are considered. ...

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Unconventional gap state of trapped exciton in lead sulfide quantum dots

Cited by 43 publications

References 53 publications

In-Gap State of Lead Chalcogenides Quantum Dots

In-Gap State of Lead Chalcogenides Quantum Dots

Comment on ‘Unconventional gap state of trapped exciton in lead sulfide quantum dots’

Strong Enhancement of PbS Quantum Dot NIR Emission Using Plasmonic Semiconductor Nanocrystals in Nanoporous Silicate Matrix

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