Preparation and characterization of heat-assisted PbS/TiO₂ thin films

Highlights: • PbS/TiO₂ thin films with different reaction temperature were prepared. • The reduction in particle size with the variation of temperature has been observed. • Film with uniform, small, and dense PbS particles was obtained at 60 °C. • The sample prepared at 60 °C possessed the highest PEC activity. - Abstract: Heat-assisted PbS/TiO₂ 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/TiO₂ thin films with reaction temperature changing from 10 to 95 °C, 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 °C 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/TiO₂ thin films have been discussed in detail