Fluorescent and nonlinear optical features of CdTe quantum dots A. A. Umar • Ali H. Reshak • M. Oyama • K. J. Plucinski Received: 3 May 2011 / Accepted: 9 June 2011 / Published online: 25 June 2011 Ó Springer Science+Business Media, LLC 2011 Abstract The study of photoluminescence and nonlinear optical properties of red (emitted at 650 nm), yellow (emitted at 570 nm) and green (emitted at 530 nm) CdTe quantum dots (QD) spin coated on quartz substrate that had been prepared by changing the ratio between octadecyl- phosphonic acid and octadecence within 0.1:1–1:1 was carried out. Spectral width of the emission spectra indicates an enhancement with the increasing of QDs sizes, namely ca. 25, 28 and 50 nm for the QD size of 2.5, 3.5 and 5 nm, correspondingly. The entire QDs samples feature a spher- ical morphology with a relatively narrow size distribution. The optical second harmonic generation (SHG) stimulated by coherent bicolor treatment at 1,540 nm and its second harmonic generation was studied versus the laser light power density and incident angle. 1 Introduction The novel nanotechnologies require search of low-sized semicondcuting materials, in particularly Quantum Dots (QDs), which are small enough (at least below 10 nm) to exhibit nano-confined effects. One of promising applica- tions of such intriguing properties is their optoelectronic and nonlinear optical features [1], determined by multi- photon absoprtion. The latter may be applied in 3D multi- photon microscopy, high sensitive tools and probes for studying of different biological and medical subjects have generated tremendous interest due to their unique optical properties. QDs are also highly efficient multi-photon absorbers that can be useful for three dimensional multi- photon microscopy and imaging, and their surfaces can be modified to conjugate biomolecules for selective targeting [2]. Their multi-photon properties are determined by third- order nonlinear optical susceptibilities. The coexistence of the nonlinear optical and optoelectronic properties such as promising emission features opens a rare possiblity of their use as materials for optoelectronic and biophotonics [3–5]. 2 Experimental The synthesis of CdTe QDs followed the Talapin method [6] with several modifications [7]. Typical procedure for the preparation of red-luminescence CdTe QDs (650 nm) is as follow: 54 mg of cadmium acetate hydrate (CH 3 COO) 2 Cd.2H 2 0 (Aldrich), 30 mg octadecylphosphonic acid (ODPA) (PCL Synthesis, USA) were dissolved in 10 mL of 1-octadecen, C 18 H 36 (Aldrich) in the presence of 0.6 mL of oleic acid (OA) (WAKO Company) at 350 °C. If using this recipe, the final concentration of ODPA and OA in the A. A. Umar Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E, Malaysia A. H. Reshak Institute of Physical Biology-South Bohemia University, Nove Hrady 37333, Czech Republic A. H. Reshak School of Material Engineering, Malaysia University of Perlis, P.O. Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis, Malaysia M. Oyama Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520, Japan K. J. Plucinski (&) Electronic Department, Military University Technology, Kaliskiego 2, 00-908 Warsaw, Poland e-mail: kpluc2006@wp.pl; kplucinski@wat.edu.pl 123 J Mater Sci: Mater Electron (2012) 23:546–550 DOI 10.1007/s10854-011-0434-6