Supra gap excitation properties of differently confined PbS-nano structured materials studied with opto-impedance spectroscopy

Nanostructures of lead sulfide (E-g similar to 0.67 to 1.7 eV) corresponding to different quantum confinement regimes (weak, moderate, and strong with radii 14, 11, and 7 nm, respectively) have been synthesized through facile aqueous colloidal method and have been capped using poly vinyl alcohol. There is a marked difference in electron-lattice coupling properties as revealed through Fourier transform infrared data with strong quantum confined PbS quantum dots (QDs) exhibiting pronounced electron-lattice coupling characteristics. Opto-impedance characteristics of these samples suggest the enhanced mobility of charges, in particular under the supra gap excitation for strong quantum confined QDs. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)