Modification of the polyol process has enabled the synthesis of nanometre-sized silver particles with a narrow size distribution. Dispersions of colloidal silver have been prepared by the reduction of silver nitrate in ethylene glycol in the presence of a polymeric protective agent, namely polyvinylpyrrolidone (PVP). Ageing these dispersions at 120 "C for 1 h yields systems with average particle sizes ranging from 15 to 36 nm. The amount of both precursor and protective agent was found to control the final particle size and size distribution of the colloidal silver, which exhibits a well crystallized structure.

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J . Phys. Chem.property. As shown in Figure 4, the electric junction starts emitting light at an applied voltage of 10 V. A similar electroluminescence diode using poly(3-alkylthiophene) spincoated on I T 0 glass has been reported? An Al/vd-PPP/Au electric junction also shows the rectification effect with a rectification ratio of about loo.As described above, the vacuum-deposited poly(ary1ene)s are electrochemically active and usable in making devices such as electrochromic devices, diodes, and electroluminescent devices. References and Notes(1) (a) Yamamoto, T.; Kanbara, T.; Mori, C. Synrh. Mer. 1990,38, 399. (b) Yamamoto, T.; Mori, C.; Wakayama, H.; Zhou, Z.-H.; Maruyama, T.; Kanbara, T.; Ohki, R. Chem. Lett. 1991, 1483. The polymers were prepared by polycondensation (e.g., Yamamoto, T.; Morita, A.; Miyazaki, Y.; Maruyama, T.; Wakayama, H.; Zhou, Z.-H.; Nakamura, Y.; Kanbara, T.; Sasaki, S.; Kubota, K. Macromolecules 1992, 25, 1214) based on organonickel chemistry (e.g., Yamamoto, T.; Yamamoto, A,; Ikeda, S. J . Am. Chem. Soc. 1971, 93, 3350). (2) E.g.: (a) Yashima, H.; Kobayashi, M.; Lee, K.-B.; Chung, D.; Heeger, A. J.; Wudl, F. Yamamoto, T.; Zama, M.; Hishinuma, M.; Yamamoto, A. J. Appl. Electrochem. 1987, 17, 607. (4) E.g.; (a) Aizawa, M.; Yamada, T.; Shinohara, H.; Akagi, K.; Shirakawa, H.J. Chem.Soc., Chem. Commun. 1986,1315. (b) Koezuka, H.; Etoh, S.

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