Highly Efficient And Stable Perovskite Solar Cells Based On Composition Regulation And Interface Engineering

In recent years,organic and inorganic hybrid perovskite solar cells have become the focus of the new generation solar cells due to its excellent photoelectric performance and low cost.After about ten years of development,its device efficiency has increased from 3.8% to over 25%,approaching the highest certification efficiency of monocrystalline silicon solar cell monocrystalline silicon solar cells,showing great application potential on the way of commercialization.Although three-dimensional perovskite materials show excellent photoelectric properties,the components contained in the structure are easily affected by environmental humidity,temperature and ultraviolet light,showing relatively poor long-term stability,which has become an important challenge in commercial application.In view of the above problems,in this paper,based on the stability of perovskite materials,highly efficient and stable hybrid perovskite solar cells were prepared by process optimization and interface dimension design,and the important role of organic spacer cations in the synergistic improvement of efficiency and stability in the low-dimensional structure of the interface was emphasized,which provided an important scientific connotation for the development of efficient and stable perovskite solar cells.This paper mainly completed the following research work:From the point of view of device physics,the carrier transport properties in the structure of perovskite solar cells were optimized to obtain high efficient perovskite solar cells as reference samples.The power conversion efficiency of perovskite solar cell devices is affected by many factors.Based on one-step spin coating method,we optimized the devices from three aspects: the composition regulation of precursor solution cation,film annealing temperature and electron transport layer.And the efficiency of the optimized perovskite solar cells reached more than 18%.The power conversion efficiency of three-dimensional structure perovskite solar cell is high,but it is easy to be affected by temperature and moisture in the air,so its stability is poor;the stability of two-dimensional structure perovskite solar cell is significantly improved due to the introduction of long chain spacer cations,but the power conversion efficiency is relatively low due to the limited charge transfer.In order to solve the problem of improving the stability and efficiency of perovskite devices,a novel space molecule,isonicotinamide,with good charge transfer ability,was designed as the cation of two-dimensional perovskite structure.The organic cation possessed the functions of both hydrophobic and charge transfer and was introduced into the three-dimensional perovskite precursor solution as additives,which resulted in the forming of a lowdimensional perovskite structure at the interface between the perovskite and the transport layer.The defects at the interface of the films were passivated effectively after the introduction of isonicotinamide,which led to the increase of carrier lifetime from 244 ns to 670 ns;The energy level structure and mott-schottky test discovered that the enhancement of Fermi level on the surface of perovskite(from-4.13 eV to-4.02 eV)enhanced the built-in electric field of photovoltaic devices and the charge extraction ability,and the best efficiency of perovskite devices increased from 18.4% to 20.4%?The study of transient photovoltage and photocurrent showed that the improvement of interface enhanced the extraction of charge carriers and inhibited the recombination of carriers.Finally,the stability including thermal stability,humidity stability and long-term stability has been significantly enhanced.The two-dimensional and three-dimensional gradient perovskite structure can improve the photovoltaic performance and stability of perovskite solar cells,which provided a new strategy for the development of highly efficient and stable perovskite solar cells.