tailieunhanh - Báo cáo hóa học: " Synthesis of Monodisperse Nanocrystals via Microreaction: Open-to-Air Synthesis with Oleylamine as a Coligand"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Synthesis of Monodisperse Nanocrystals via Microreaction: Open-to-Air Synthesis with Oleylamine as a Coligand | Nanoscale Res Lett 2009 4 344-352 DOI S11671-009-9251-8 NANO EXPRESS Synthesis of Monodisperse Nanocrystals via Microreaction Open-to-Air Synthesis with Oleylamine as a Coligand Hongwei Yang Ningning Fan Weiling Luan Shan-tung Tu Received 19 October 2008 Accepted 8 January 2009 Published online 22 January 2009 to the authors 2009 Abstract Microreaction provides a controllable tool to synthesize CdSe nanocrystals NCs in an accelerated fashion. However the surface traps created during the fast growth usually result in low photoluminescence PL efficiency for the formed products. Herein the reproducible synthesis of highly luminescent CdSe NCs directly in open air was reported with a microreactor as the controllable reaction tool. Spectra investigation elucidated that applying OLA both in Se and Cd stock solutions could advantageously promote the diffusion between the two precursors resulting in narrow full-width-at-half maximum FWHM of PL 26 nm . Meanwhile the addition of OLA in the source solution was demonstrated helpful to improve the reactivity of Cd monomer. In this case the focus of size distribution was accomplished during the early reaction stage. Furthermore if the volume percentage vol. of OLA in the precursors exceeded a threshold of the resulted CdSe NCs demonstrated long-term fixing of size distribution up to 300 s. The observed phenomena facilitated the preparation of a size series of monodisperse CdSe NCs merely by the variation of residence time. With the volume percentage of OLA as in the source solution a 78 nm tuning of PL spectra from 507 to 585 was obtained through the variation of residence time from 2 s to 160 s while maintaining narrow FMWH of PL 26-31 nm and high QY of PL 35-55 . Keywords Quantum dots Microreaction Reaction kinetics Size control H. Yang N. Fan W. Luan El . Tu School of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China e-mail luan@ .