Temperature-Dependent Photoluminescence of CdSe-Core CdS/CdZnS/ZnS-Multishell Quantum Dots

Jing, Pengtao; Zheng, Jinju; Ikezawa, Micho; Liu, Xueyan; Lv, Shaozhe; Kong, Xianggui; Zhao, Jialong; Masumoto, Yasuaki

doi:10.1021/jp902080p

Cited by 231 publications

(248 citation statements)

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“…There is also a continuous red shift of the PL peak with increasing temperature, which is consistent with low-temperature studies where the shift in band gap is described by the Varshni equation. 9,12 The shift is totally reversible (Supporting Information, Figures S2 and S3).…”

Section: Articlementioning

confidence: 99%

“…Traps and defects have been used to explain luminescence quenching above 50 K for organically capped CdSe 11 and CdTe 10 QDs. For coreÀshell QDs, the quenching temperature increased to 200 K or above RT for CdSe/ CdS/ZnS multishells 12 or CdSe/CdS nanorods. 23 These observations suggest that thermal quenching of QDs is related to carrier trapping in (surface) defect states, and surface passivation through inorganic shells can suppress this process.…”

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confidence: 99%

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High-Temperature Luminescence Quenching of Colloidal Quantum Dots

et al. 2012

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A high luminescence efficiency is an important property of colloidal quantum dots (QDs), and quantum yields higher than 90% have been reported for coreÀshell QDs. 1 High efficiencies are especially important for application of QDs as luminescent biolabels, 2 in QD lasers, 3 in spectral converters for warm white LEDs, 4,5 electroluminescent devices, 6 and solar concentrators. 7 Luminescence efficiencies are strongly temperature-dependent. 8 Extensive temperature-dependent luminescence studies for colloidal QDs have been conducted at cryogenic temperatures (0.3À300 K). 9À15 In this temperature region, interesting effects were observed, including a prolonged lifetime below 20 K related to brightÀdark state splitting, 11,16 thermally activated quenching due to surface defect states, 9,10,17 and temperature antiquenching assigned to a phase transition in the capping layer. 14,15 However, the luminescence properties of QDs above room temperature (RT) are hardly investigated, and yet, for most applications in luminescent devices, the working temperature is higher than 300 K. An interesting example is the recent application of QDs as color converters in warm-white LEDs, 18 in which QDs serve as narrow band red emitters under excitation with blue light from a (In,Ga)N LED. The narrow emission bandwidth renders QDs superior to classical phosphors based on broad band emission from luminescent ions. 19 In high-power LEDs for general lighting applications, the heat generated in the pÀn junction and phosphor converter layer leads to temperatures as high as 150À200°C in the layer applied on top of the blue diode. 20 To avoid these high temperatures, the QD phosphor layer can be placed in a more remote configuration. Still, temperatures in such a configuration are expected to be well above 50°C due to heat dissipation of the QDs themselves (excess energy from converting the blue into red light). Clearly, the quenching of QD luminescence at elevated temperatures is relevant for application of QDs in luminescent devices, and a better insight in the quenching behavior is needed.Despite its importance, research on luminescence temperature quenching above RT is very limited for QDs. It is theoretically expected for a QD to have a very high luminescence quenching temperature (T q ). Three generally accepted mechanisms for thermal quenching involve thermally activated crossover from the excited state to the ground state, multiphonon relaxation, and thermally activated photoionization. The first mechanism is generally depicted in a simple configurational coordinate diagram. 8,21 The energy difference between the minimum * Address correspondence to a.meijerink@uu.nl.Received for review July 18, 2012 and accepted September 14, 2012. Published online 10.1021/nn303217qABSTRACT Thermal quenching of quantum dot (QD) luminescence is important for application in luminescent devices. Systematic studies of the quenching behavior above 300 K are, however, lacking. Here, high-temperature (300À500 K) luminescence studies are reported for highly ef...

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Section: Articlementioning

confidence: 99%

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confidence: 99%

High-Temperature Luminescence Quenching of Colloidal Quantum Dots

et al. 2012

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“…We have used Γ 0 = 32.5 meV from ref. 10 following their linear fit at a low temperature range of 10-50 K. Further, based on the Raman spectra measurements of CdSe NPLs 10 and QDs, 12 we have taken ħω LO = 25 meV, to fit the other parameters of eqn (11) using the ascending temperature data from Fig. 8b.…”

Section: −T/τ2mentioning

confidence: 99%

“…Achtstein et al 10 studied NPL characteristics at the cryogenic range, while there are several works studying QDs and other nanocrystals across varying temperature ranges. [11][12][13] But, work addressing the study of NPL optoelectronic properties at elevated temperatures above RT has not been reported thus far. We begin by laying down the theoretical framework, followed by a comprehensive discussion on the obtained results to understand the physics of the NPLs at elevated temperatures, and present experimental methods at the end.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent optoelectronic properties of quasi-2D colloidal cadmium selenide nanoplatelets

et al. 2017

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Colloidal cadmium selenide (CdSe) nanoplatelets (NPLs) are a recently developed class of efficient luminescent nanomaterials suitable for optoelectronic device applications. A change in temperature greatly affects their electronic bandstructure and luminescence properties. It is important to understand how and why the characteristics of NPLs are influenced, particularly at elevated temperatures, where both reversible and irreversible quenching processes come into the picture. Here we present a study of the effect of elevated temperatures on the characteristics of colloidal CdSe NPLs. We used an effective-mass envelope function theory based 8-band k·p model and density-matrix theory considering exciton-phonon interaction. We observed the photoluminescence (PL) spectra at various temperatures for their photon emission energy, PL linewidth and intensity by considering the exciton-phonon interaction with both acoustic and optical phonons using Bose-Einstein statistical factors. With a rise in temperature we observed a fall in the transition energy (emission redshift), matrix element, Fermi factor and quasi Fermi separation, with a reduction in intraband state gaps and increased interband coupling. Also, there was a fall in the PL intensity, along with spectral broadening due to an intraband scattering effect. The predicted transition energy values and simulated PL spectra at varying temperatures exhibit appreciable consistency with the experimental results. Our findings have important implications for the application of NPLs in optoelectronic devices, such as NPL lasers and LEDs, operating much above room temperature.

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“…However, they showed drastic reduction in their intensity with increasing amount of Pb in the precursor solution. In general, emission from semiconductor nanocrystals is composed of band-edge emission and emission from surface trap states (Saunders et al, 2008;Jing et al, 2009). Temperature-dependent PL spectroscopy is often used to study the radiative and the non-radiative relaxation process in nanocrystals.…”

Section: Wwwintechopencommentioning

confidence: 99%