tailieunhanh - Báo cáo hóa học: " The Role of Intrinsic and Surface States on the Emission Properties of Colloidal CdSe and CdSe/ZnS Quantum Dots Giovanni Morello Æ Marco Anni Æ Pantaleo Davide Cozzoli "

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: The Role of Intrinsic and Surface States on the Emission Properties of Colloidal CdSe and CdSe/ZnS Quantum Dots Giovanni Morello Æ Marco Anni Æ Pantaleo Davide Cozzoli | Nanoscale Res Lett 2007 2 512-514 DOI s11671-007-9096-y NANO EXPRESS The Role of Intrinsic and Surface States on the Emission Properties of Colloidal CdSe and CdSe ZnS Quantum Dots Giovanni Morello Marco Anni Pantaleo Davide Cozzoli Liberato Manna Roberto Cingolani Milena De Giorgi Received 11 May 2007 Accepted 4 September 2007 Published online 22 September 2007 to the authors 2007 Abstract Time Resolved Photoluminescence TRPL measurements on the picosecond time scale temporal resolution of 17 ps on colloidal CdSe and CdSe ZnS Quantum Dots QDs were performed. Transient PL spectra reveal three emission peaks with different lifetimes 60 ps 460 ps and 9-10 ns from the bluest to the reddest peak . By considering the characteristic decay times and by comparing the energetic separations among the states with those theoretically expected we attribute the two higher energy peaks to 1U and 1L bright states of the fine structure picture of spherical CdSe QDs and the third one to surface states emission. We show that the contribution of surface emission to the PL results to be different for the two samples studied 67 in the CdSe QDs and 32 in CdSe ZnS QDs confirming the decisive role of the ZnS shell in the improvement of the surface passivation. Keywords Colloidal Quantum Dots Optical properties Time resolved photoluminescence Introduction Colloidal II-VI highly luminescent nanocrystals are important both in fundamental studies due to their peculiar G. Morello El M. Anni P. D. Cozzoli L. Manna R. Cingolani M. De Giorgi National Nanotechnology Laboratory NNL of CNR-INFM Distretto Tecnologico ISUFI Universita del Salento Via per Arnesano Lecce 73100 Italy e-mail M. Anni Dipartimento di Ingegneria dell Innovazione Universita del Salento Via per Arnesano Lecce 73100 Italy optical properties and in technological applications such as diodes lasers photovoltaic cells. In the last years great improvement in the Quantum Yield QY has been obtained by

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