Zinc Oxide Buffer Layer:Magnetron Sputtering And Its Application In Antimony Selenide Thin Film Solar Cells

By means of photoelectric effect,solar cells transform abundant and clean solar energy to electricity which provides a way to solve the energy crisis and environment problems.Among the numerous types of solar cells,thin film solar cells have attracted wide publicity because of the outstanding properties thin film solar cell possesses.People have noticed the toxicity of Cd element and the limited reserves of Te element in the successful commercialized CdTe thin film solar cells as well as the high costs of In and Ga in CIGS solar cells.People have constantly been searching for the optimal absorber materials with non-toxic,low-costs and large-potential properties.As a non-toxic and earth-abundant material,antimony selenide（Sb₂Se₃）emerges as a promising solar cell material with lager absorption coefficients and suitable bandgap.Generally chemical bath deposited CdS film is used as the buffer layer and Sb₂Se₃ film is evaporated via RTE method in traditional high-efficiency Sb₂Se₃ thin film solar cells,which in fact,fails to achieve the complete green solar cells.The toxicity of CdS leads to the potential threat to environment with plenty of waste water containing Cd which needs to be dealed with after the film deposition.Magnetron sputtering zinc oxide based materials overcome the shortcomings meationed above,and in the industrail manufacture,vacuum method is the most commonly used method which possessed high repeatabilities,clean deposition process,high efficiencies of producting properties.The already commercialized CdTe and CIGS thin film solar cells have got to use the complete vacuum method.So the complete vacuum method of Sb₂Se₃ thin film solar cells have an important significance to the industrialized mass production of Sb₂Se₃ thin film solar cells.The thesis studied the magnetron sputtering ZnO buffer layer application in Sb₂Se₃ solar cells.And the thesis mainly includes the following points:（1）The thesis successfully fabricates ZnO film by magnetron sputtering,and the defect-related deep level emissions under different annealed atmospheres are carefully investigated by the photoluminescence（PL）.It reveals that the oxygen vacancy predominates the point-defects in ZnO film and the ambient annealing process on ZnO indeed passivates the ZnO interface leading to reducing oxygen vacancy defect densities,thus,improving the film quality.Simultaneously,a series of electric characterization of ZnO/Sb₂Se₃ heterojunction like C-f,C-V and DLCP profiling prove the diminished interface trap densities via ZnO ambient annealing procedure,the decreasing interface states generate less interface recombinations and promotes device performance.The diode parameters calculations using Site’s method also demonstrate the improved P-N junction quality via the ambient annealing treatment.Based on that,we achieve the 4.08%efficiency superstrate（Glass/FTO/ZnO/Sb₂Se₃/Au）solar cell.（2）To enhance the doping density of ZnO,another AZO film attaches to the ZnO film leading to suitable Zn（Al,O）buffer layer,which is prepared by sputtering.The wider bandgap and the higher doping density bring the improvements in short-circuit current and open-circuit voltage,results in the better superstrate 4.37%efficiency Sb₂Se₃ solar cells;（3）Furthermore we explore the high c-axis orientation Sb₂Se₃ thin film fabrication with brand new method of Sb₂Se₃ deposition,for the purpose of improving the orientation of（002）of Sb₂Se₃ on ZnO film.The new method provides a new idea of realizing high-efficiency antimony selenide thin film solar cells based on the solid foundation.