Abstract

This results of the experimental investigation of the synthesis and characterization of Silver Sulphide Quantum Dots is presented. In this work, silver quantum dots were synthesized using the Successive Ionic Layer Adsorption and Reaction (SILAR) technique. Different numbers of SILAR circles, ranging from four to ten circles of Silver Quantum Dots were synthesized. Tin II Chloride was used as the reducing agent which reduces silver hydroxide to silver. A colourless substrate immersed in the container of Tin II chloride solution before its immersion in the container of silver nitrate solution was observed to be brown which increases with the number of SILAR cycles as a result of the formation of silver quantum dots on it. The number of cycles directly determines the size of the quantum dots produced. Exposure of these substrates with silver quantum dots to hydrogen sulphide for 10minutes in a fume chamber using the Kipp’s apparatus converted the silver quantum dots to silver sulphide quantum dots thereby making the substrates to become dark brown. The synthesized Quantum Dots were characterized using UV-SPEC2048 Spectroscopy machine. The absorption spectra exhibit a blue shift with decreasing size of silver sulphide quantum dots. This is due to the quantum size effect. The band gap of silver sulphide quantum dots with their respective sizes was calculated and it was found that the average band gap of the synthesized silver sulphide quantum dot is 1.80eV. This is higher than the band gap of bulk silver sulphide semiconductor which is about 0.9eV.