Photoacoustic study of alloyed Cd1−xPbxS quantum dots sensitized solar cells electrodes

Abstract

The optical properties of ternary alloyed Cd1−xPbxS (x: 0, 0.33, 0.5, 0.67 and 1) quantum dots (QDs) photoanodes are studied using photoacoustic (PA) technique. Ternary alloyed Cd1−xPbxS QDs were adsorbed onto TiO2 electrodes using successive ionic layer adsorption and reaction technique. The structural properties of the prepared QDs photoanodes have been investigated. X-ray diffraction measurements confirm the formation the cubic crystalline structures of the ternary alloyed Cd1−xPbxS QDs photoanodes. The elemental analysis of the ternary alloyed Cd1−xPbxS QDs were studies using an energy dispersive X-ray spectrometer. The optical properties of the ternary alloyed Cd1−xPbxS QDs photoanodes have been studied with PA technique, UV–visible spectrophotometer and photoluminescence spectrofluorometer. The energy band gap of the prepared ternary QDs alloys decreases from 2.74 to 1.87 eV as x value increases from 0 to 1.0. This red shift in the energy band gap is due to alloying and Pb incorporation. The modified Vegard’s model is used to calculate the bulk values of the energy band gap of alloyed Cd1−xPbxS. Also, the bowing parameter of the ternary alloyed Cd1−xPbxS QDs is determined and equal 0.49 eV. The size of the prepared alloyed QDs are calculated for both CdS QDs (x = 0) and PbS QDs (x = 1) using the effective approximation (EMA) model and found 2.06 and 2.09 nm respectively.