W₁₈O₄₉and W₁₈O₄₉@Al₂O₃:Preparation,Characterization And Application On Perovskite Solar Cells

With the development of optoelectronic technology,the requirements for inorganic semiconductor materials are more stringent.However,it is difficult to find or prepare new materials suitable for the field of optoelectronics.Therefore,in-depth research and modification of the discovered materials is the focus of current research work.W18O49 as a non-stoichiometric oxide,is relatively chemically stable,but slowly oxidizes when the temperature is too high.Amorphous Al2O3 is a chemically stable oxide,and amorphous Al2O3 has low crystallinity and defective level in the band gap,similar in nature to semiconductor materials.The defect level of Al2O3 is similar to that of semiconductor materials,so the combination of W18O49 and Al2O3 is expected to improve the stability of W18O49 while maintaining its original photoelectric performance W18O49 microrods are stable one-dimensional structures with excellent optical and electrical properties.It is necessary and important to realize the controllable preparation of W18O49 microrods.Therefore,the main research work of this thesis is as follows:1.Controlled synthesis of W18O49 microrods used pyrolysis-reduction process through tuning both 5%H2 gas flow and heated temperature.The results suggest that W18O49 microrods will grow well when calcined at 650 ?for 2 h under 10 L/h 5%H2 gas flow.The crystal structure of W18O49 has been refined by Rietveld refinement with the GSAS program.A fitted lattice parameter value is that,a:18.340 A,b:3.788 A,c:14.025 A,p:115.168°.Measurement result of the sheet resistance of samples indicates that pure W18O49 microrods exhibit a resistivity as low as 0.068 2 cm.2.The coated W18O49@Al2O3 is prepared by ultrasonic sol-gel method and further high temperature sintering.The W18O49@Al2O3 was synthesized by controll the content of Al2O3 and W18O49 microrods and the heated temperature.The optimum preparation conditions of W18O49@Al2o3 determined by TEM,SEM,XRD and UV spectroscopy.the mass ratio of W18O49:Al2O3 = 100:1 and the heated temperature was 500 °C.Through the HRTEM analysis of W18O49@Al2O3,it is found that the Al2O3 in the W18O49@Al2O3 exists in the crystalline state and the amorphous state.There is a boundary between W18O49 and Al2O3.The simulated solar photocatalytic experiment determined that the photocatalytic efficiency was up to 87%when W18O49:Al2O3 =100:1.3.Firstly,the perovskite material CsPbBr3 was prepared and the CsPbBr3 was characterized.The optimal preparation conditions of CsPbBr3 as active layer were explored and further assembled into inorganic perovskite solar energy.The results showed that the spin coating speed of 2000 rpm was the optimum preparation condition for the active layer material CsPbBr3.With W18O49 as the electron transport material(FTO/TiO2/CsPbBr3/W18O49/Carbon),the inorganic PSC efficiency of assembly is up to 2.3%;while the W18O49@Al2O3 is used as the electron transport material(FTO/TiO2/CsPbBr3/W18O49@Al2O3/Carbon),the inorganic PSC is assembled,and the efficiency decreases with the increase of the mass ratio of Al2O3:W18O49 in the W18O49@Al2O3,the mass ratio of W18O49:Al2O3 = 100:1 with an efficiency of up to 1.3%.