Fine Control of Red–Green–Blue Photoluminescence in Zeolites Incorporated with Rare-Earth Ions and a Photosensitizer
✍ Scribed by Yuji Wada; Mutsuko Sato; Yasunori Tsukahara
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 308 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0044-8249
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✦ Synopsis
Red-green-blue (RGB) photoluminescent crystals have recently merited considerable attention because of their potential application to optoelectronic devices such as fullcolor displays. [1][2][3] Energy transfer has been demonstrated in the photosensitization of metal complexes, [4] dendrimers, [5] phosphors, [6] and electroluminescence devices. [7] However, the control of energy transfer to multiple components for multicolored luminescence [8, 9c] has so far been extremely difficult because of the sensitivity of luminescence systems to their chemical environments. Nanohybrid systems using zeolites appear to be good candidates to overcome such difficulties. [9] Herein, we report rare-earth-ion-exchanged zeolites incorporated with a photosensitizer (Figure 1 A) that exhibit successful RGB photoluminescence depending on which rare-earth ions and photosensitizers are used (Figure 1 B). The color can also be finely tuned by varying the temperature and the excitation wavelength.
The sodium form of faujasite-type zeolite, Na-X (SiO 2 / Al 2 O 3 = 2.46, Na/Al = 1.0; Tosoh Co.), was stirred in an aqueous solution of Ln(NO 3 ) 3 •6 H 2 O (Ln = Tb, Eu; 0.08 m ; [Tb III ]/[Eu III ] = 10:0, 10:1, 1:1, and 0:10) for 16 h at 353 K to exchange the sodium ions with Ln III ions. The products were removed by centrifugation, then washed with deionized water, and dried in air at 353 K. The Ln III -exchanged zeolites were degassed at 423 K for 1 h for dehydration and were then either exposed to benzophenone (bzp) vapor at 373 K for 16 h or stirred in a solution of 4-acetylbiphenyl (acbp) in ethanol at room temperature for 20 h. The resulting samples were then degassed at room temperature for 5 h. The reaction sequence was carried out on a vacuum line to avoid exposure of the zeolites to the atmosphere.
The percentages of Tb and Eu in the zeolites were determined by inductively coupled plasma techniques (Jobin