Research On Buffer Layer Of Sb₂Se₃ Thin Film Solar Cells

Solar cell is a device that can transform solar energy to electricity. It helps people to transform and use solar energy effectively. Among different types of cells, thin film solar cells arouse wide intersts due to their outstanding performances. In particular, CIGS and CdTe solar cells are well studied. However, In and Ga are expensive, and Cd is toxic, thus we're eager to make cheaper and non-toxic solar cells. It is found that Sb2Se3 possesses a large absorption coefficient and sutiable bandgap. In addition, its components, Sb and Se, are both abundant and non-toxic. These features make Sb2Se3 an excellent material to be absorb layer. In this thesis, we mainly investigated applications of Sb2Se3 thin film in planar heterojunction solar cells.In this thesis, the vacuum evaporation method was studied to deposit Sb2Se3 thin films. Different characteriazations, such as SEM, XRD, XPS and UV-vis, were applied to analyze the perporities of Sb2Se3 thin films deposited by various processes. It turns out that Sb2Se3 thin film deposited at a high temperature and high rate shows better properities which are more suitable for making efficient solar cells. Depending on characterization results, the best process was determined for Sb2Se3 film depostion. After that, CdS and Zn-based buffer layers were combined with the Sb2Se3 thin film to form a heterojunction solar cell, respectively.In this thesis buffer layer were depoisted by chemical bath deposition(CBD) and spray pyrolysis. A comprehensive understanding of principle for CBD guides us to deposit CdS film. According to characterization results, it's known that the post-treatment makes CdS film flat and compact. Then, a Sb2Se3 solar cell was made by using CdS film as the buffer layer. Its efficiency reached over 2%. Since Cd is toxic to the environment, we carried out the research on non-toxic Zn-based film in order to replace CdS solar cells. CBD and spray pyrolysis methods were utilized to fabricate Zn-based films, mainly including ZnO and ZnS(O,OH). Films with different S rate can be achieved by changing the composition of precursors for CBD and spray pyrolysis. Sb2Se3 thin film solar cells were made by using Zn-based buffer layers with different S rates. The performances of these cells vary a lot, and the highest efficiency can reach beyond 2%.