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Monodisperse ZnO and ZnSe nanoparticles with extremely strong UV-photoluminescence

Alexey S. Shaporev 1Vladimir K. Ivanov 1,2Andrey A. Eliseev 2

1. Kurnakov Institute of General and Inorganic Chemistry RAS (IGIC), Leninsky prospect, 31, Moscow 119991, Russian Federation
2. Faculty of Material Science, Moscow State University (MSU), Lenin Hills, Moscow 119992, Russian Federation

AIIBIV semiconductor nanoparticles attract close attention of the researchers due to their size-dependent optical and electrical properties. They possess effective luminescence in UV region of spectra, and are highly prospective for transparent electrodes for solar cells, electro-luminescent devices, chemical sensors etc. Here, we describe a new route to prepare ZnO and ZnSe nanoparticles with ultra narrow size distribution. The method was based on usual TOP/TOPO preparation procedure. ZnO and ZnSe were synthesized from diisopropyl zinc, with TOPO or TOPSe as BIV element source (for ZnO and ZnSe, correspondingly) and oleic acid as a surface active compound. The reactions were carried out at 1800C under argon flow (5 min). ZnO and ZnSe colloidal solutions were subjected to size selective precipitation procedure and redispersed in heptane.

Synthesized materials were studied by HRTEM, UV-Vis and luminescent spectroscopy. According to TEM, they consist of 3-5 nm nanoparticles with rather narrow size distribution. The particles are well separated and no aggregates were observed. Obtained colloidal solutions showed strong excitonic absorbtion peaks in UV region. The band edges are blue-shifted compared to bulk materals, and particle sizes calculated from UV-Vis absorbtion spectra are in a good agreement with those observed by TEM. It should be noted that no absorbance in visible region was found at all. Obtained materials demonstrate good photoluminescent properties: ZnO has an intense luminescence in UV region (346 nm, excitonic emission) and low-intensity wide green line with maximum at 538 nm (defect). Variation of synthetic conditions allowed us to form ZnO nanostructures with UV/Vis emission ratio up to 50 at room temperature. Emission from ZnSe nanostructures was found much less intensive than that of ZnO. However nearly the same UV/Vis emission ratio was observed.
This work was supported by FCNTP (project 02.513.11.3217) and RFBR (project 05-03-33036).


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium A, by Alexey S. Shaporev
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-21 12:25
Revised:   2009-06-07 00:44