Antimony Selenide Thin Film Solar Cells Based On Non-toxic Titanium Oxide Buffer Layer

Solar cell,a device that transforms solar energy to electricity utilizing photovoltaic effect,nowadays received extensive attention because of energy shortage.Among various types of solar cells,flexible thin-film solar cells could be applied into many different fields.In recent years,the preparation techniques of CdTe and CIGS solar cells are mature and applied into commercialization.However,cadmium is highly toxic,meanwhile In and Ga are expensive metals.So we require a candidate absorption layer with non-toxic and cheap material.Sb₂Se₃ has attracted extensive research attention in photovoltaics due to its non-toxicity,low cost and earth-abundant constituents.So Sb₂Se₃ is a promising choice as an absorption layer in thin-film solar cells.Sb₂Se₃ thin-film solar cells were deeply researched in past several years.The excellent device efficiency was acquired on CdS-based N-type buffer layer.Although the device structure is mature,the toxicity will restrict its development in the future.In this thesis,we use non-toxic and wide-bandgap TiO₂ as the buffer layer instead of toxic CdS.The TiO₂ film was prepared by spray-pyrolysis method,which is a promising industrialization method because of its low-cost,high utilization of raw materials and large-area preparation.In present research methods,when optimizing a craft parameter,ones will fetch values one after another and compare the results to get the optimum parameter.It's really a time-consuming and tedious method,and the samples prepared by this way can't be highly uniform with respect to fixed processing parameters.To solve this problem,we introduce high-throughput approach,which is a good new way to complete a large number of samples within a short time,which offers the promise of rapid and efficient materials screening,optimization,and discovery.By high-throughput approach,key parameters such as TiO₂ thickness,post-annealing temperature and Sb₂Se₃ thickness are identified.Furthermore,by means of back surface treatment with?NH₄?₂S solution,5.6%efficiency of TiO₂/Sb₂Se₃ was obtained.During this process,we study the interface defects of TiO₂/Sb₂Se₃ in detail with a lot of material and electrical characterizations,such as XRD,XPS,PL,C-V and DLCP,indicating that decreasing the concentration of interface defects is the key of improving the device efficiency.To further improve the efficiency of TiO₂/Sb₂Se₃ solar cells,we study the Sb₂Se₃ film deposited on TiO₂ by vapor transfer deposition?VTD?method.After studying the deposition process,morphology and orientation,we obtain high?221?and?211?orientation of Sb₂Se₃ thin film.Finally,the highest efficiency of TiO₂/Sb₂Se₃ device is achieved as 5.82%.