Enhanced phosphorescence and electroluminescence in triplet emitters by doping gold into cadmium selenide/zinc sulfide nanoparticles

Liu, Hong Wei; Laskar, Inamur Rahaman; Huang, Chin Ping; Cheng, Jung An; Cheng, Shih Shun; Luo, Liqiang; Wang, Huei Ru; Chen, Teng‐Ming

doi:10.1016/j.tsf.2005.04.094

Cited by 10 publications

(5 citation statements)

References 27 publications

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“…[14][15][16][17][18][19][20][21][22][23][24][25] One of the promising applications of doped semiconductor NCs is solid state lighting based on AC electroluminescent (EL) devices that are expected to have high electrical-to-light conversion efficiency. [26][27][28][29][30][31][32] Cubic ZnS with a bulk bandgap of 3.7 eV is a common and attractive choice as a host semiconductor for doping to produce nanophosphors in EL applications due to its stability, low cost, and low toxicity. 26,27,30,[32][33][34][35][36] A number of metal ions, such as Mn 2+ , Cu + , Pb 2+ , Ag + , and Eu 2+ , have been successfully doped into ZnS to produce PL or EL emission in different regions of the visible spectrum.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, semiconductor nanocrystals (NCs) have drawn significant attention due to their unique structural, electronic, and optical properties originating from their large surface-to-volume (S/V) ratio and quantum confinement effect. − An important subset of semiconductor NCs are those doped with a small percentage of dopants to alter their electronic, magnetic, and optical properties for various desired applications. − One of the promising applications of doped semiconductor NCs is solid state lighting based on AC electroluminescent (EL) devices that are expected to have high electrical-to-light conversion efficiency. − …”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Structural, and Optical Properties of Stable ZnS:Cu,Cl Nanocrystals

et al. 2009

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Stable water-suspendable Cu+-doped ZnS nanocrystals (NCs) have been synthesized with mercaptopropionic acid (MPA) as a capping molecule. The nanocrystals have been characterized using a combination of experimental techniques including UV-vis and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and extended X-ray absorption fine structure (EXAFS). The UV-vis electronic absorption spectrum shows an excitonic peak at 310 nm, characteristic of quantum-confined ZnS NCs. This excitonic peak does not change noticeably with Cu+ doping. XRD confirms the formation of ZnS nanocrystals, and the average size of the NCs has been determined to be around 6 nm by TEM. The incorporation of Cu+ into the ZnS is manifested as a substantial red-shift of the emission band in the PL spectra upon addition of Cu2+ that was reduced into Cu+ during the synthesis reaction. EXAFS data were obtained to confirm copper doping as well as determine the local structure about Cu+ and Zn2+ in the NCs. Fitting to the EXAFS data for Cu+ suggests that most Cu+ ions are located near the surface within the ZnS NCs and that a significant fraction may be in the form of CuS as found in bulk material. These combined optical and structural studies have provided important new insight into the relevant electronic energy levels and their correlation to the optical and structural properties of ZnS:Cu,Cl NCs. This has important implications in potential applications of this phosphor material for solid state lighting, imaging, and other photonic devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, Structural, and Optical Properties of Stable ZnS:Cu,Cl Nanocrystals

et al. 2009

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“…The emitted light comes from the polymer, and the QDs are added to the host matrix to improve the device efficiency. Generally speaking, the enhancement of the performance is due either to a better charge injection [21][22][23][24] or to an energy transfer from QDs to the electroluminescent material [25]. However, when a QD layer is formed inside the film from a phase separation in the composite [26], it can block the injected holes and electrons by high-energy barriers that are formed in the emitting layer, and allows a balance in the charge transport, thus improving the device performance.…”

Section: Introductionmentioning

confidence: 99%

Traps and performance of MEH-PPV/CdSe(ZnS) nanocomposite-based organic light-emitting diodes

et al. 2008

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We report the fabrication and investigations of organic light-emitting diodes (OLEDs) using a composite made by mixing poly[2-methoxy-5(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with CdSe/ZnS core/shell quantum dots (QDs). The electroluminescence efficiency of the studied devices was found to be improved as compared to devices using MEH-PPV. Moreover, the current density decreased with increasing QD concentration. We checked the effects of QDs on the electrical transport by determining the trap states, making use of the charge-based deep level transient spectroscopy (Q-DLTS) technique. The most striking result obtained is the decrease in trap density when adding QDs to the MEH-PPV polymer film. These results suggest that QDs would heal defects in nanocomposite-based devices and that CdSe/ZnS QDs prevent the trap center formation.

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“…CdSe/ZnS core-shell type quantum dots (QDs) passivated with trioctylphosphineoxide (TOPO) caps were prepared following the technique already described [22]. The size of the dots used in this work was 3.8 nm as determined from transmission electron microscopy (TEM).…”

Section: Methodsmentioning

confidence: 99%