Surface Modification Of ZnO/SnO₂ Materials By An Ionic Liquid In Perovskite Solar Cells

With the continuous development of human society,traditional fossil energy and other non-renewable energy sources are constantly consumed,and their products have also caused serious pollution on the environment.Therefore,it is particularly important to find new types of clean energy that can be used sustainably.Using solar energy to achieve high-efficiency,low-cost photoelectric conversion is an ideal way to solve energy and environmental problems.In recent years,perovskite solar cells?PSCs?that the organometallic halides CH₃NH₃PbX₃?MAPb X3,X = Br,I,Cl?are light absorbing layers,which has rapidly received worldwide attention and has become one of the hottest research directions in the field of photovoltaics due to its advantages of high efficiency and low-cost manufacture.In this work,we introduce an ionic liquid?IL?of 1-ethyl-3-methylimidazolium hexafluorophosphate?[EMIM]PF₆?as an surface modification layer in the ZnO-based PSCs.The efficient and stable devices are fabricated in air without any atmosphere controlling.Experimental results show that the introduction of the IL layer enhances the electron collection and transport capability of the ZnO electron transport layer,forming a denser perovskite film,reducing surface defect states.The photoelectric conversion efficiency of the device increases from 11.80 % to 13.50 %,and the hysteresis of the battery is also decreased.More importantly,after 90 days?> 2000 h?storage in air,our device without encapsulation retains 88.17 % of its initial efficiency.Our work provides a simple valid strategy to develop air-processed,stable and efficient PSCs for future applications.In this experiment,we also introduce an ionic liquid of 1-ethyl-3-methylimidazolium hexafluorophosphate?[EMIM]PF6?as an surface modification layer in the SnO₂-based PSCs.The efficient devices are fabricated in air without any atmosphere controlling.Experimental results show that the introduction of ionic liquids enhances the electron collection and transport capability of the SnO₂ electron transport layer,promotes the growth of large-size perovskite crystal grains.The reduction of grain boundary effectively reduces surface defects,the photoelectric conversion efficiency of the PSC is significantly improved from 13.54 % to 15.19 %.Our work provides a simple valid strategy to develop air-processed and efficient PSCs for future applications.