Preparation and characterization of heat-assisted PbS/TiO_2 thin films

摘要

Heat-assisted PbS/TiO_2 thin films with different reaction temperatures were prepared. Microstructure, morphology, optical and photoelectron-chemical properties of the as-synthesized thin films were investigated systematically. For the PbS/TiO_2 thin films with reaction temperature changing from 10 to 95℃, PbS particles obtained by successive ionic layer adsorption and reaction are galena phase, the mean size of PbS particles decreases firstly and then increases, the coverage of PbS particles on surface increases. At the same time, red shift in the adsorption edges from 416 to 594 nm has been detected, and the optical band gap E_g decreases from 3.58 to 2.88 eV. What's more, the intensity of photoluminescence increases firstly and then decreases. The photochemistry measurement suggests that the sample prepared at 60 ℃ possesses the highest photocurrent in the first test cycle. However, the value of photocurrent decreases immediately with increasing the test cycle. The effect of the reaction temperature on the microstructure, morphology, optical and photoelectron-chemical properties of PbS/TiO_2 thin films have been discussed in detail.