Study On The Effect Of Vanadium Oxide On The Performance Of Perovskite Solar Cells

With the increasing awareness of human environmental protection,clean energy is gradually replacing polluting fossil fuels.Solar energy has aroused widespread concern as a representative of renewable green energy.Solar cells directly convert inexhaustible solar energy into non-renewable electricity,injecting new vitality into the field of new energy.Perovskite solar cells?PSCs?have become the new star in the field of solar cells due to the excellent photoelectric properties of perovskite materials.Since 2009,in just eight years,a series of important breakthroughs have been made in the photoelectric conversion efficiency?PCE?of PSCs,from less than 4%to more than 22%.Although the high efficiency has been obtained,the stability of the device structure and performance is still a major obstacle to its commercial application.It is an important research direction to improve the device performance and promote the commercialization of PSCs by adding interfacial modification layer and active layer with additives.The main contents of this thesis include the following three parts.First,the effect of V₂O₅ hole-modifying layer on the performance of PSCs is studied.V2O5 thin film is added as an interfacial layer between the poly?3,4-ethylene dioxy-thiophene?–poly?styrene sulfonate??PEDOT:PSS?hole transport layer and the indium tin oxide?ITO?electrode,achieving a PCE of 15.49%.The results show that the V₂O₅modified layer can reduce the roughness of the hole transport layer film and improve the crystal quality of the perovskite thin film.The V₂O₅ helps to promote the absorption of sunlight by the perovskite active layer,enhancing the photoelectric properties of the devices.In addition,the V₂O₅ interfacial layer can block acidic PEDOT:PSS diffusion to ITO electrode,maintaining the stability of the device structure and effectively increasing the lifetime of the device.Then,the effect of solution-treated V2Ox interface layer on the performance of PSCs is studied.V₂O₅ reacts with H₂O₂,obtaining V₂O_x corresponded to different valence state of V element.The comparison of the different positions of V₂O_x films shows that the V₂O_x interface layer between the PEDOT:PSS hole transport layer and the ITO helps to obtain the best optoelectronic properties of the device.V2Ox film as the interface layer can effectively enhance the charge transfer and inhibit the recombination of electron-hole pairs.When the molar ratio of V₂O₅ to H₂O₂ is controlled to 1:60,the device achieved a PCE of 15.86%.Final,the effect of photoactive layer with V₂O_x additive with on the performance of PSCs is studied.The study finds that most of the V elements are distributed on the boundaries of perovskite grain.We speculate that the reaction of V₂O₅ and H₂O₂ produced V₂O₅·H₂O₂,and the hydrogen bonds in hydrates favor the formation of high-density and large-size perovskite films.Meanwhile,CH₃NH₃PbI_3-xCl_x:V₂O_x heterojunction is formed in the photoactive layer,which facilitates the separation and transmission of carriers,and a 16.14%of PCE has been obtained of device prepared in air obtains.Moreover,the device has good stability.Unencapsulated devices still maintain more than 80%of initial PCE after being stored in the air for 360 hours.