Study On Germanium Selenide Thin Film Deposited By Vacuum Methods And Its Solar Cell

GeSe,as a IV-VI chalcogenide,has been considered as a potential absorber material due to the advantages of suitable band gap?1.14 eV?,large absorption coefficient(>10⁵cm^-1),remarkable air stability,earth-abundant and low-toxic constituents.Up to now,the research on GeSe thin film and its corresponding device is relatively scarce,which is reflected in the following aspects:?i?Deposition methods are relatively simple,and some commonly used methods in industry?such as magnetron sputtering and vacuum themal evaporation?have not been applied to prepare GeSe films.?ii?Many properties of GeSe films have not been explored,such as phase transition,recrystallization and growth mechanism of GeSe films.?iii?GeSe thin film solar cells have disadvantages such as open-circuit voltage and low poper conversion efficiency.Based on the above problems of GeSe material and its thin film solar cells,this work systematically studied and analyzed the preparation of GeSe thin film solar cells by vacuum depositions of GeSe precursor films combined with different post-annealing processes.In chapter 1,the solar cells were classified,the latest research status of various solar cells was sorted out,and the structure,basic principles and related performance parameters of the solar cells were introduced in detail.The characteristics of GeSe materials,the research status of GeSe materials and the research status of GeSe thin film solar cells were introduced in detail.The main research contents of this work were presented in the last part of this chapter.In chapter 2,GeSe precursor thin films were prepared by radio-frequency magnetron sputtering.The phase transition process and recrystallization process of GeSe precursor film at different annealing temperatures were studied systematically.After annealing,it was found that when the annealing temperature was 400°C,the pure phase and good crystal GeSe film could be prepared.The band gap of GeSe thin film was found to be 1.14 eV by ultraviolet-visible spectrophotometer?UV-vis?.The suppersrate FTO/CdS/GeSe/Carbon/Ag thin film solar cells were assembled,achieching an open-circuit voltage of 220 mV,a short-circuit current density of 0.82 mA/cm²,a filling factor of 26.50%and a power conversion efficiency of 0.05%.In chapter 3,GeSe precursor films were deposited by vacuum thermal evaporation.The effects of different post-annealing methods on GeSe precursor films were investigated.It was found that the sandwichingg post-annealing treatment not only inhibited the secondary sublimation of GeSe,but also improved the crystallinity of GeSe samples,formed?100?preferred orientation GeSe films.The open-circuit voltage of the GeSe thin film solar cells was further increased to 340 mV by assembling the broad band-gap TiO₂ and?100?oriented GeSe thin film to form TiO₂/GeSe heterojunction thin film solar cells.Through capacitive-voltage profiling analysis?C-V Profiling?and driver-level capacitance profiling analysis?DLCP?,it was found that the two main factors limiting the performance improvement of GeSe thin-film solar cells were narrow depletion width?138 nm?and TiO₂/GeSe interface recombination.