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- Chen, W, et al.
(author)
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Full-Color Emission and Temperature Dependence of the Luminescence in Poly-P-phenylene ethynylene-ZnS/Mn2+ Composite Particles
- 2003
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 107:27, s. 6544-6551
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Journal article (peer-reviewed)abstract
- The synthesis of a nanocomposite material composed of anionic poly(phenylene ethynylene) (aPPE) polymer particles and ZnS/Mn2+ nanoparticles is described, and its luminescence properties are investigated. aPPE particles have two emissions, one in the blue (460 nm) and the other in the green (490 nm), that are assigned to the 0-0 transition and an excimer, respectively. ZnS/Mn2+ nanoparticles have an emission at 596 nm that is due to the T-4(1)-(6)A(1) transition of Mn2+ and an emission at 706 nm that is ascribed to defect-related luminescence. The blue, green, yellow, and red emissions make the composite a potential material for full-color displays. More interestingly, the relative intensities of the different emissions may be varied by changing the excitation energy. Infrared spectra reveal that interactions exist between the two particles; however, photoluminescence excitation and emission spectra as well as observations of luminescence lifetimes indicate that there is negligible energy transfer from the polymer particles to the ZnS/Mn2+ nanoparticles. Temperature studies reveal that the ZnS/Mn2+ particles in the nanocomposite have a significantly reduced thermal quenching energy relative to that of bare ZnS/Mn2+ nanoparticles. In addition, between room temperature and 90 degreesC, the luminescence of the ZnS/Mn2+ nanoparticles at 596 nm increases in intensity with increasing temperature. This surprising phenomenon is attributed to thermoluminescence and thermal curing of the particle surface upon heating.
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| 2. |
- Chen, W, et al.
(author)
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Full-color emission from In2S3 and ln(2)S(3): Eu3+ nanoparticles
- 2004
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 108:32, s. 11927-11934
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Journal article (peer-reviewed)abstract
- New observations on the luminescence Of In2S3 and europium-doped In2S3 nanoparticles show a green (5 10 nm) emission from In2S3 and In1.8Eu0.2S3 nanoparticles while a blue (425 nm) emission is observed from ln(1.6)Eu(0.4)S(3) nanoparticles. Both the blue and green emissions have large Stokes shifts of 62 and 110 nm, respectively. Excitation with longer-wavelength photons causes the blue emission to shift to a longer wavelength while the green emission wavelength remains unchanged. The lifetimes of both the green and blue emissions are similar to reported values for excitonic recombination. When doped with Eu3+, in addition to the broad blue and green emissions, a red emission near 615 nm attributed to Eu3+ is observed. Temperature dependences on nanoparticle thin films indicate that with increasing temperature, the green emission wavelength remains constant, however, the blue emission shifts toward longer wavelengths. Based on these observations, the blue emission is attributed to exciton recombination and the green emission to Indium interstitial defects. These nanoparticles show full-color emission with high efficiency, fast lifetime decays, and good stability; they are also relatively simple to prepare, thus making them a new type of phosphor with potential applications in lighting, flat-panel displays, and communications.
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