RESEARCH PAPER Studies of the photostability of CdSe/CdS dot-in-rod nanoparticles Xiaoming Wen • Amit Sitt • Pyng Yu • Hsien-chen Ko • Yon-Rui Toh • Jau Tang Received: 14 July 2012 / Accepted: 30 October 2012 / Published online: 15 November 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Fluorescent CdSe/CdS dot-in-rod nano- particleshaveattractedconsiderable interestfor fundamental research and potential applications in bioscience and physical science. In this work,we investigated photoinduced phenomena in CdSe/CdS dot-in-rodsusing time-resolved photoluminescence (PL). Our experimental results show that photopass- ivation,photooxidation, and photoinduced defect/ surface states occurin CdSe/CdS dot-in-rods, and these processes depend on the irradiation amount. The thickness of the CdS shell plays an important role for photostability. Photopassivation was found to initially result in an increase of PL intensity when fluence is low. Photooxidation was found to cause a spectral blue shift due to shrinkage of the core. We also found that a thick shell of CdS can effectively suppress photoox- idation and hinder the diffusion of oxygen into the core.Irradiation could generate defect/surface states predominantly in the shell and also on the interface between the core and the shell. A weak PL shoulder in the blue side was observed in heavily irradiated samplesas a resultof photoinduced ruptureof encapsulation. Keywords CdSe/CdS dot-in-rod Photooxidation Photopassivation Fluorescence Seeded growth Introduction Colloidal core/shell semiconductor nanoparticles hav shown great potential for applications in optoelec- tronic devices, such as light-emitting diodes (LEDs), lasers,and photovoltaic cells (Peng et al. 2000; Carbone et al. 2007;Reiss et al. 2009),due to their uniqueopticaland electronicproperties, such as linearly polarized absorption and emission (Milliron et al. 2004; Talapin et al. 2004; Hikmet et al. 2005), high quantum-yield fluorescence (Talapin et al. 2004 Gudiksen et al. 2005;Muller etal. 2005),and one- dimensional electrical transport (Steiner et al. 2004, 2008). In particular, recently developed high quality seed-grown core–shell nanorods, in which a CdS rod- like shellwas grown onto a spherical nanocrystal, revealseveral advantageous properties for optoelec- tronic applications (Mokari and Banin 2003; Talapin et al. 2003, 2007;Carbone et al. 2007;Dorfs etal. 2008; Sitt et al. 2009), such as a narrow distribution nanorod length and diameter, a high quantum yield, linearly polarized fluorescence, and tunable emission wavelength which is controlled by the dimension of X. Wen (&) P. Yu H. Ko Y.-R. Toh J. Tang (&) Research Center for Applied Sciences, Academia Sinica, Taipei,Taiwan e-mail: xwen@gate.sinica.edu.tw J. Tang e-mail: jautang@gate.sinica.edu.tw A. Sitt The Center for Nanoscience and Nanotechnology, The Hebrew University, 91904 Jerusalem, Israel 123 J Nanopart Res (2012) 14:1278 DOI 10.1007/s11051-012-1278-6