Enhanced Ultraviolet Light Stability Of Hybrid Perovskite Materials With ZnO/TiO₂ Composite Film

The organic-inorganic hybrid perovskite materials with advantages of suitable bandgap,high light absorption coefficient,high mobility,have excellent performance in solar cells.But hybrid perovskite materials are prone to decompose under ultraviolet irradiation,which seriously affects the application of solar cells.Using ultraviolet filter with high absorbance in the ultraviolet region and high transmittance in the visible region can improve hybrid perovskite ultraviolet light stability.It is an important approach for the practical application of the hybrid perovskite photovoltaic device.Traditional organic UV absorbing films use organic molecules,which have poor sunlight resistance and thermal stability.Inorganic semiconductor materials with good UV shielding effects,such as ZnO,TiO₂,etc.,have good chemical stability and thermal stability and high visible light transmittance,are more suitable for UV filter materials for solar cells.Therefore,this work chose inorganic UV filter film for the research topic,we prepared ZnO/TiO2 composite film with good UV filter effect below100?.And studied the enhancment effect of hybrid perovskite materials ultraviolet light stability.The specific research content is as follows:1.Preparation of ZnO/TiO₂ composite UV filter:ZnO nanoparticles were synthesized by colloidal chemical method,and the size of ZnO nanoparticles was regulated by rapid hydrolysis,which caused red shift of the absorption edge and extended the UV absorption range;ZnO nanoparticle films were prepared by spin coating.The TiO2 layered composite films were prepared by photodecomposition at room temperature using Titanium diisopropoxide bis?acetylacetonate?as precursor.TiO2 improve hardness and stability of the composite films.By optimized conditions,ZnO/TiO2 composite ultraviolet filter films with ultraviolet shielding ratio of 8.5%?200-400 nm?and visible light transmittance of 96%were prepared.2.Study on perovskite ultraviolet stability with ZnO/TiO₂ composite film:The CH3NH3PbI3 hybrid perovskite film was synthesized by a two-step method,the perovskite film was covered with ZnO/TiO2 composite UV filter film under ultraviolet light?365 nm,81mW/cm²?.After irradiation,the surface morphology of CH₃NH₃PbI₃ film remained intact and the absorbance had no obvious decrease.The XRD pattern showed no peak of PbI2.Compared with the sample without protection of UV filter after same irradiation,pinholes appeared on the surface of the perovskite film,and absorbance decreased significantly.The peak of PbI2 in the XRD pattern was enhanced.It proved that the stability of the hybrid perovskite under ultraviolet light improved by using the ZnO/Ti O2 composite film.Further we parpared hybrid perovskite solar cell and put it under same ultraviolet light?365 nm,81mW/cm²,600 min?irradiation.The efficiency of the device protected by the filter film was maintained at 77%of the initial value,while the efficiency of the unprotected device was decreased to 9%.The device decay speed was significantly slower,proving that the filter film can improve the UV stability of perovskite solar cells and prolonged the service life of the devices.