Defect Control And Photovoltaic Performance Of Antimony Selenide Solar Cells

Antimony selenide(Sb2Se3)has attracted much attention in the field of inorganic thin-film solar cells.Sb2Se3 has several outstanding advantages:simple binary phase,excellent photovoltaic properties and abundant element reserves.In a few years,the efficiency of Sb2Se3-based solar cell has approached around 10%,but the efficiency is far from meeting the standard of practical applications.A further improvement of device efficiency requires a more comprehensive and in-depth understanding of the internal Sb2Se3 defects;on the other hand,it is also important to optimize the device structure and interface property.This thesis focuses on the efficiency improvement of antimony selenide solar cells,mainly carrying out the following parts of the research content:Chapter 1:The basic properties of Sb2Se3,the preparation process of thin films and the development status of Sb2Se3 solar cells were investigated in detail.Moreover,the key factors for efficiency improvement of Sb2Se3 based solar cells were analyzed.On this basis,the research topics of this thesis were proposed.Chapter 2:Ethylenediamine-thiol solvent system was applied to the preparation of solution-processed Sb2Se3 thin films,and Tellurium-doped Sb2Se3 thin films were successfully prepared by this method.The doping of Tellurium in Sb2Se3 films could make a fine regulation of the film components.More importantly,the doping of Tellurium could effectively passivate hole traps in Sb2Se3.As a result,the carrier life of Sb2Se3 film was increased obviously.By the optimization of Tellurium doping concentration,the efficiency of Sb2Se3-based solar cells was significantly increased compared with the undoped Sb2Se3-based device.The champion efficiency is 5.4%,which is also the highest efficiency for the solution-processed Sb2Se3 solar cells.This work provides an effective strategy to reduce the deep defects in Sb2Se3,which could also inspire the defect research of other antimony-based chalcogenide devices.Chapter 3:All-inorganic n-i-p structured Sb2Se3 solar cells were constructed by introducing the solution-processed MOS3 film as hole transport layer.There is a suitable energy level aligment between MOS3 and Sb2Se3,and the deposition of hole transport layer is beneficial to reduce the surface roughness and back contact resistance.Moreover,the preparation of MOS3 film could gently eliminate the antimony oxide impurity on the Sb2Se3 film surface,thus improving the device interface properties.The FTO/CdS/Sb2Se3/MoS3/Au structured solar cell finally achieved an efficiency of 6.86%.In terms of device stability,inorganic material MoS3 shows its unique advantages.This work provides an efficient inorganic hole transport material with simple preparation process,environmental protection,non-toxic and strong stability for Sb2Se3 solar cells.Chapter 4:A compact Sb2Se3 interfacial layer was introduced by hydrothermal deposition.The conduction type,energy level aligment and composition between the Sb2Se3 interfacial layer and Sb2Se3 thin film deposited thermal evaporation were demonstrated to have slight difference.The optimized interfacial layer could not only realize the dominant growth of[hk1]orientation,but also improve the grain size and film compactness.On this basis,the device with FTO/CdS/Sb2Se3/Spiro-OMeTAD/Au structure was prepared,and the CdS/Sb2Se3 interface properties and the device efficiency were improved.This work combines the advantages of chemical deposition method and physical deposition method;thus the film has higher crystallinity and stronger bond with CdS layer.This work provides a strategy for the induction of thin film orientation and the improvement of interface properties.Chapter 5:The research focus of this thesis was summarized,and the limitations of the work were analyzed.Finally,the prospect of the defect control and the improvement of photoelectric performance for antimony selenide solar cells was made.