| The electron transport layer in perovskite solar cell is very important to the performance of solar cell.Among them,TiO2 is one of the most widely used materials in perovskite solar cells due to its advantages of large bandgap,long electronic life and low preparation cost.At present,perovskite solar cells with anatase or rutile phase TiO2 as the electron transport layer have achieved good photoelectric properties.However,the researches on the influence of phase structure on electronic transmission performance are not systematic,and the researches on anatase and rutile mixed phase TiO2 as electron transport layer are relatively less.Besides,the electron mobility of TiO2 is relatively low,which will affect its electronic transmission ability.In order to solve the above problems,based on the positive planar perovskite solar cells,the effect of different titanium sources and Li+doping on the morphology,crystal shape regulation and energy level regulation properties of TiO2 thin films were studied in this paper.Through the preparation of thin films,characterization of morphology and structure,device building,photoelectric performance testing,the effects of the structure regulation of TiO2 on the photovoltaic performance of devices were explored.In order to obtain high-quality perovskite films,the effect of chlorobenzene dropping time and different rotational speeds on the film-forming behavior of perovskite films were studied by one-step anti-solvent method.The results showed that the appropriate chlorobenzene dropping time and rotating speed could significantly increase the conversion of PbI2,and further improved the quality and crystallinity of perovskite thin films.On the basis of obtaining the optimal preparation process of perovskite thin films,the device achieved 7.97%power conversion efficiency under one-sun illumination.Then,on the foundation of obtaining good perovskite thin films,the effects of different titanium sources on the properties of the prepared TiO2 thin films were studied by using titanium diisopropoxy diacetylacetone and tetrabutyl titanate,respectively.Compared with titanium diisopropoxy diacetylacetone,titanium dioxide obtained from tetrabutyl titanate source had better energy level matching and stronger electron extraction ability than that obtained from titanium diisopropoxy diacetylacetone.The device which was prepared from titanium source of tetrabutyl titanate combined with optimized perovskite thin film,the power conversion efficiency was 8.59%.Ion doping has a significant effect on the crystal structure and photoelectric properties of TiO2.Therefore,Li+was used to dope the solution of tetrabutyl titanate and to control the crystal phase composition by controlling the concentration of Li+doping.The results showed that with the addition of Li+,the anatase phase of TiO2 gradually transformed into rutile phase,and the prepared samples had good transmittance.The optical band gap of titanium dioxide decreased to 3.63 eV when the content of Li+doping was 5.0%,the film resistivity at 5.0%was the smallest and the electron extraction effect was the strongest.On this basis,the power conversion efficiency of the perovskite solar cell was 9.14%. |
