Morphological, structural, optical and electrical properties of PbS nanocrystals doped with Fe2+ grown by chemical bath

Doping of PbS nanocrystals with Fe2+ions leads to changes in properties that make them useful in technology of thin films devices. In this paper we present the growth of PbS doped systematically with the solution containing the Fe2+ ions (V[Fe2+]) using the green chemical bath approach, with the goal of studying the effects of such Fe2+-doping on the morphological, structural, electrical and some optical properties of the PbS thin films obtained. The morphological changes of the films were followed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). X-ray diffraction showed growth of all films in the zinc blende phase. The grain size was found to be ∼29 and ∼21-17 nm, for the undoped and doped sample, respectively. The absorbance showed in doped films a weak shoulder located at ∼625 nm (1.98 eV), and this exciton peak was attributed to a 1Se → 1Sh transition. A shift for the band gap energy was observed by optical absorption from ∼1.56 eV for the undoped sample to ∼2.20-2.25 eV range for the doped films. The resistivity increased from ∼26.13-295.7 (Ω cm), and with respect to the electrical conductivity, mobility decreased from ∼8.8 × 10−4-2.1 × 10−7 (Ω cm)−1, ∼720.1-2.1 cm2 V−1 s−1 and carrier from ∼1.9 × 1015-4.2 × 1012 cm−3, while increasing V[Fe2+].