Fabrication Of Sb₂(S_1-xSe_x)₃ Thin Films By Solution Method And The Investigation Of Solar Cell Properties

The antimony sulfide-selenide(Sb2(S1-xSex)3)materials have attracted widespread attention in the field of solar energy application since it possesses suitable optical band gap,abundant elemental storage and excellent stability.As an emerging photoelectronic material,the current research direction mainly includes the fabrication of high-quality Sb2(S1-xSex)3 thin films,the exploration of well-matched functional layers and the optimization of device structure.In this thesis,solution process was applied in the preparation of Sb2(S1-xSex)3 thin films and the precursor solution was prepared by selected source materials and solvents.The Sb2(S1-xSex)3 thin films were prepared by spin coating and annealing program.We explored the effects of different Se/S atomic ratios,different interface layers and different amount of additives on the properties of Sb2(S1-xSex)3 thin films,including their morphology,crystal structure,composition,band gap,energy level position and internal defects.Further,through the assembling of solar cell devices,the influence rules of the above conditions on the device performance were investigated and revealed.The content of this thesis can be summarized into the following five parts:Chapter 1:The study background,working principle and classification of solar cells were systematically introduced.The characteristics of antimony sulfur selenide thin-film materials and the current status of Sb2(S1-xSex)3 based solar cell development were detailedly described.On this basis,the main research content of this thesis was proposed.Chapter 2:A new solution system was introduced to control the S/Se atomic ratio in Sb2(S1-xSex)3 films.In this study,by preparing Sb-S-Se complex solution,one-step spin coating method was used to prepare Sb2(S1-xSex)3 thin film.First of all,we explored the dissolution mechanism of elemental Se by electron paramagnetic resonance spectroscopy test of the precursor solution.We found that elemental Se is present in the precursor solution as Se-N radicals.Then,by controlling the amount of Se in the precursor solution,the S/Se ratio in the film could be effectively adjusted.A further study found that the S/Se atomic ratio has a significant effect on the morphology,composition,band gap,energy level position and device performance of the Sb2(S1-xSex)3 film.Finally,a device photoelectric conversion efficiency of 5.8%was obtained when the film composition was Sb1.9S2.2Se0.9.This study provided a simple method for preparing band gap-adjustable Sb2(S1-xSex)3 films.Chapter 3:A method of interface modification was developed to further optimize the performance of Sb2(S1-xSex)3 thin film solar cells prepared by one-step solution method.Cadmium sulfide(CdS)and indium-doped cadmium sulfide(In:CdS)films were deposited by chemical water bath deposition and were used as the interface layer to modify the titanium dioxide(TiO2)electron transport layer.In this study,we analyzed the morphology,band gap,energy level position of the two interface layers,and explored the influence of the two interface layers on the morphology of the Sb2(S1-xSex)3 thin film and the device performance.The results showed that the roughness of the In:CdS interface layer is relatively larger,which could effectively improve the density of the Sb2(S1-xSex)3 film.As a result,the denser film enhanced the utilization of incident light and reduced carrier recombination.Besides,the energy level of In:CdS thin film material is between TiO2 and Sb2(S1-xSex)3,so the establishment of interface structure is conducive to charge separation and transport.Finally,the photoelectric conversion efficiency of the Sb2(S1-xSex)3 thin-film solar cell was increased to 6.63%.This study revealed that the interface modification based on In:CdS is an effective method to improve the performance of Sb2(Si-xSex)3 thin film solar cells.Chapter 4:A new solution system and spin coating process were introduced for Sb2(S1-xSex)3 thin film fabrication.The Sb2Se3 precursor film was first prepared by spin coating,and the Sb2S3 film was then prepared onto it.The Sb2(S1-xSex)3 film was obtained after high temperature annealing.We found that using a small amount of H2O as an additive could regulate the growth process of the film.The effect of the content of H2O in the reactant on the morphology,crystal structure,composition,band gap,defects of the Sb2(S1-xSex)3 film and device performance were analyzed.The results showed that adding appropriate amount of H2O could effectively increase the grain size and reduce the type and concentration of defects,which would improve the transport of carriers and reduce recombination probability.The photoelectric conversion efficiency of 7.42%was finally obtained.This study provided a new research idea for regulating the growth process of Sb2(S1-xSex)3 thin film and improving device efficiency.Chapter 5:The research content of this paper was summarized,and the shortcomings and problems were analyzed.Finally,advices were proposed to look forward the development direction of the solution method.