ZnS-AgInS2 Solid Solution Nanoparticles Research Articles

Efficient quantum-dot light-emitting diodes using ZnS–AgInS2 solid-solution quantum dots in combination with organic charge-transport materials

Colloidal quantum dots (QDs), which exhibit highly saturated color emission, are expected to be used as emitting materials in wide-color-gamut displays. However, the development of low-toxicity alternatives is necessary because QDs with high color purity and highly efficient emission contain toxic materials such as Cd and Pb. In this study, QD light-emitting diodes (QD-LEDs) with ZnS–AgInS2 solid-solution nanoparticles [(AgIn)xZn2(1−x)S2, ZAIS] as low-toxicity QDs were fabricated and their electroluminescence properties were investigated. The ZAIS QDs exhibited red photoluminescence, with a peak wavelength of ca. 700 nm. Because the charge-injection barrier of ZAIS QDs without a wide-bandgap shell is relatively low, the QD-LEDs with red ZAIS QDs in combination with organic charge-transport materials induce electron injection from an organic electron-transport layer. These QD-LEDs exhibit an external quantum efficiency of 2.2%, a turn-on voltage of 2.4 V, and red emission with chromaticity coordinates (0.66, 0.33).

Adipose Tissue-Derived Stem Cell Imaging Using Cadmium-Free Quantum Dots.

Quantum dots (QDs) have received much attention for biomolecule and cell imaging applications because of their superior optical properties such as high quantum efficiency, size-tunable emission, and resistance to photobleaching process. However, QDs that are commercially available contain cadmium (Cd), a highly toxic element. Thus, the development of Cd-free and less toxic QDs is strongly desired. In this study, we developed Cd-free QDs (ZnS-coated ZnS-AgInS2 solid solution nanoparticles with a sulfo group: ZnS-ZAIS-SO3H) and investigated the ability of this material to label stem cells. ZnS-ZAIS-SO3H could be transduced into mouse adipose tissue-derived stem cells (mASCs) using octaarginine peptides (R8), known as cell-penetrating peptides. The optimal ratio of ZnS-ZAIS-SO3H:R8 was found to be 1:100 for labeling mASCs. More than 80% of mASCs labeled with 500 nM ZnS-ZAIS-SO3H were found to be alive, and the proliferation rates of labeled mASCs were maintained at the same rate as that of nonlabeled mASCs. In addition, no abnormalities in the morphology of mASCs labeled with ZnS-ZAIS-SO3H could be observed. These data suggest that ZnS-ZAIS-SO3H may be effective for the labeling of mASCs.

Photoinduced Electron Transfer of ZnS–AgInS2 Solid-Solution Semiconductor Nanoparticles: Emission Quenching and Photocatalytic Reactions Controlled by Electrostatic Forces

The electron transfer between the fluorescent ZnS–AgInS2 solid-solution (ZAIS) nanoparticles (NPs) and redox species is investigated in an aqueous solution in terms of chemosensors and photocatalysts. In a case where the ZAIS NPs and quenchers are oppositely charged, very efficient photoluminescence (PL) quenching (KS ≈ 106 M–1) is observed because of the specific adsorption of quenchers on particles. The quenching magnitude increases with the potential gap between the photoexcited NPs and quenchers. Methyl viologen (MV2+) shows the largest quenching behavior; i.e., it is revealed to quench most of PL by the adsorption of only a single molecule. In such a case, the linearity of quenching magnitude is lost, and distribution of the quencher adsorption on NPs should be considered to clarify the quenching mechanism. In the opposite case where both the ZAIS NPs and quenchers are negatively charged, although the quenching efficiency is two to three orders of magnitude lower than that in the aforementioned adsor...

(Invited) Photosensitization of ZnO Nanorod Electrodes with ZnS-AgInS2 Solid Solution Nanoparticles

not Available.

Long Term Optical Properties of ZnS-AgInS2 and AgInS2-AgGaS2 Solid-Solution Semiconductor Nanoparticles Dispersed in Polymer Matrices

Long term optical properties of fluorescent I-III-VI semiconductor nanoparticles and its solid solution dispersed in the methacrylate resin were tested under various conditions aiming at their use as wavelength converters. The ZnS-AgInS2 solid solution nanoparticles, which we developed recently, have less stability against a thermal and a photonic stimulus, while the AgInS2-AgGaS2 solid solution nanoparticles maintain an acceptable fluorescence property even after 1000 h of a thermal stimulus. Differences in the durability between the two types of semiconductors are discussed based on the solid solubility. The deterioration of the fluorescence property is considered to be due to the phase separation of crystals of ZnS-AgInS2 system.

Immobilization of ZnS–AgInS2 Solid Solution Nanoparticles on ZnO Rod Array Electrodes and Their Photoresponse with Visible Light Irradiation

Abstract ZnS–AgInS2 solid solution (ZAIS) nanoparticles having elements of low toxicity were immobilized on thin ZnO rod array films, and the resulting film worked as an n-type semiconductor electrode for which the photoresponse varied depending on the composition of particles immobilized.

Remarkable photoluminescence enhancement of ZnS–AgInS2 solid solution nanoparticles by post-synthesis treatment

The photoluminescence intensity of ZnS-AgInS(2) solid solution nanoparticles was remarkably enhanced by increasing the heating temperature to 180 degrees C, above which the emission was simply diminished, while ZnS coating of the particles resulted in further enhancement of PL intensity, giving the highest quantum yield of ca. 80%.