Recently, the team headed by Li Can and Liu Shengzhong, Researchers of the Department of Solar Energy Research, Department of Solar Energy Research, Department of Solar Energy, National Institute of Clean Energy, Chinese Academy of Sciences, Dalian, China, cooperated with Dr. Yang Dong from Shaanxi Normal University to develop a planar perovskite solar energy New progress has been made in the research of batteries, and the related research results are published in the journal Energy & Environmental Science. Perovskite materials have been shown to be extremely large in cheap solar cells and other optoelectronic devices due to their excellent photoelectric properties such as large extinction coefficient, long carrier lifetime, high charge mobility, long migration distance and very low defect state density The application value. Perovskite solar cells, high-performance electronic transmission materials to improve the efficiency of the device is essential. In the previous work, the team made the first use of soluable low temperature processing method to prepare solid ionic liquids with high light transmittance and high electron mobility as electron transport materials, and successfully prepared flexible perovskite cells with an efficiency of 16.09% The highest efficiency of mine flexible devices. In this work, the team modified the titanium oxide electron transport material with ionic liquids to improve the electron mobility, reduce the surface roughness, and at the same time make the Fermi level shift up, which is conducive to the export of electrons in the device. The planar perovskite solar cells prepared based on the above transmission materials have an efficiency of 19.62%, which is the highest efficiency of the perovskite planar devices. The study also found that the anion in the ionic liquid is combined with the titanium oxide, and the cation is combined with the perovskite to form an effective electron transport channel between the perovskite and the titanium oxide so that the electrons in the device can be extracted and transmitted well. In addition, the defect state density of the perovskite thin films grown on the IL-modified titanium oxide electron transport material is low, which greatly inhibits the recombination of carriers in the device and further improves the battery performance. The research results provide a new effective way to prepare high efficiency perovskite solar cells. The research work was supported by the National Key Research and Development Program, the "111 Program" by the National Natural Science Foundation of China and Innovation Team, the Changjiang Scholars and the "Thousand Talents Program".