Photophysical and structural characterisation of <i>in situ</i> formed quantum dots

Bansal, Ashu K.; Antolini, F.; Sajjad, Muhammad T.; Stroea, Lenuta; Mazzaro, Raffaello; Ramkumar, S. G.; Kass, Kim-Julia; Allard, Sybille; Scherf, Ullrich; Samuel, Ifor D. W.

doi:10.1039/c4cp00727a

Cited by 22 publications

(21 citation statements)

References 35 publications

(38 reference statements)

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“…These results are in correlation with the results obtained by TEM and PLQY measurements and suggest that QDs can be formed under different baking conditions but the nanoparticle aggregation takes place at higher temperatures with a consequent decrease in QD PLQY as it was previously observed. In comparison to our earlier published work 21 where we used a polymer blended with this precursor, here we have shown that the thermolysis also works well with a small charge transporting molecule, and go on to demonstrate laser photo-patterning.…”

Section: Structural Characterization Of Nanocomposite Films Of Tpbi Amentioning

confidence: 67%

“…The CdDMASe precursor film also absorbs in UV with peak absorbance below 280 nm but does not show any emission even when excited at different excitation wavelengths from 280 to 380 nm. 21 We have also measured the photoluminescence quantum yield of the TPBI neat film using an integrating sphere purged with nitrogen and found it to be 45% when the film was excited at 305 nm.…”

Section: Resultsmentioning

confidence: 99%

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In situ formation and photo patterning of emissive quantum dots in small organic molecules

et al. 2015

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Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. Here we report a novel method for the fabrication and patterning of metal selenide nanoparticles in organic semiconductor films that is compatible with solution processable large area device manufacturing. Our approach is based upon the controlled in situ decomposition of a cadmium selenide precursor complex in a film of the electron transporting material 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBI) by thermal and optical methods. In particular, we show that the photoluminescence quantum yield (PLQY) of the thermally converted CdSe quantum dots (QDs) in the TPBI film is up to 15%. We also show that laser illumination can form the QDs from the precursor. This is an important result as it enables direct laser patterning (DLP) of the QDs. DLP was performed on these nanocomposites using a picosecond laser. Confocal microscopy shows the formation of emissive QDs after laser irradiation. The optical and structural properties of the QDs were also analysed by means of UV-Vis, PL spectroscopy and transmission electron microscopy (TEM). The results show that the QDs are well distributed across the film and their emission can be tuned over a wide range by varying the temperature or irradiated laser power on the blend films. Our findings provide a route to the low cost patterning of hybrid electroluminescent devices.

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Section: Structural Characterization Of Nanocomposite Films Of Tpbi Amentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

In situ formation and photo patterning of emissive quantum dots in small organic molecules

et al. 2015

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“…We should note that the QD solution has a longer fluorescent lifetime of 55 ns. The faster response of the QD film is due to an increase in the nonradiative decay rate as the QD molecules are aggregated within the film [31], [32]. The fluorescence spectrum of the QD film is also shown in the inset of Fig.…”

Section: Resultsmentioning

confidence: 96%

Effects of Injection Current on the Modulation Bandwidths of Quantum-Dot Light-Emitting Diodes

Xiao

et al. 2019

IEEE Trans. Electron Devices

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This article presents an investigation of the modulation bandwidths of quantum-dot (QD) light-emitting diodes (QLEDs). The QLEDs used in our study are redemissive CdSe/ZnS QLEDs, which have a structure of indium tin oxide (ITO)/poly(3.4-ethylene-dioxythiophene) polystyrene sulfonate (PEDOT:PSS)/TFB/QD/ZnO/Al and an emitting area of 2 or 4 mm 2. We find that at a small injection current (below ∼10 mA), the effects of the resistance-capacitance (RC) time constant and the carrier lifetime on the bandwidths of the QLEDs are comparable, while at a large injection current, the bandwidths are mainly determined by the carrier lifetime. The response time of the QDs is not a limiting factor. The bandwidths of the QLEDs increase with the injection current and are eventually limited by the damage threshold current of the devices. At the same injection current, the QLED that has a smaller emitting area provides a larger current density, and thus exhibits a larger bandwidth. At an injection current of 28 mA, the 2-mm 2 QLED provides a bandwidth of 11.4 MHz and a luminance value of 156 000 cd/m 2 , and the 4-mm 2 QLED provides a bandwidth of 8.2 MHz and a luminance value of 97 000 cd/m 2. Our investigation provides a guideline for QLED-bandwidth optimization and useful information for the further development of QLEDs for lighting, display, and communication applications.

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“…A cluster shell comprising CdSe QDs surrounded by functionalized C 60 molecules exhibited a superior photocurrent response, with ultrafast electron transfer between the CdSe QD and the functionalized fullerene . An alternative method was developed for the in situ generation of CdSe QDs in a polymer nanocomposite film through thermal decomposition of a complex cadmium precursor blended with the polymer …”

Section: Photovoltaics Applicationmentioning

confidence: 99%

Conjugated Polymer/Nanocrystal Nanocomposites for Renewable Energy Applications in Photovoltaics and Photocatalysis

Lin

Hsu

et al. 2014

Small

101

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Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed.

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Photophysical and structural characterisation of in situ formed quantum dots

Cited by 22 publications

References 35 publications

In situ formation and photo patterning of emissive quantum dots in small organic molecules

In situ formation and photo patterning of emissive quantum dots in small organic molecules

Effects of Injection Current on the Modulation Bandwidths of Quantum-Dot Light-Emitting Diodes

Conjugated Polymer/Nanocrystal Nanocomposites for Renewable Energy Applications in Photovoltaics and Photocatalysis

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