Study On The Hybrid Electron Transport Layers For High-efficiency Perovskite Solar Cells Regulated By Ionic Liquid Materials

Perovskite solar cells have a wide range of raw materials,simple preparation processes,and high photoelectric conversion efficiency.It is currently the hotspot of international frontier research.The electron transport layer is one of the important factors affecting the photoelectric conversion efficiency of perovskite solar cells.The high-quality electron transport layer plays a vital role in improving the interface contact,the quality of the perovskite film and the photovoltaic performance of the Perovskite solar cells.Ionic liquid materials have shown excellent performance in the field of perovskite solar cell due to their unique physical and chemical properties.The research work of this thesis has developed two different types of electron transport layers.One is a low-temperature in-situ ionic liquid-assisted microwave TiO₂ electron transport layer and hybrid electron transport layer,the other is a new type Ionic liquid electron transport layer and a high-efficiency hybrid electron transport layer.The main content is as follows:1.Research on low-temperature in-situ ionic liquid-assisted microwave TiO₂（IL-TiO₂）electron transport layer and hybrid electron transport layer.First,we developed a low-temperature,fast in-situ IL-TiO₂ electron transport layer preparation method with 1-carboxymethyl-3-methylimidazole bistrifluoromethanesulfonimide.We prepared the electron transport layer with different reaction time by in-situ microwave method with a low temperature of 70 ^oC.Compared with the TiO₂electron transport layer without adding ionic liquid,the perovskite light absorbing layer prepared on IL-TiO₂ electron transport layer has significantly improved film quality,stability,light absorption performance,and fluorescence performance.The perovskite solar cell based on IL-TiO₂-15min achieved a photoelectric conversion efficiency of 19.55%,which is greatly improved by 17.5%.Secondly,we further constructed the IL-TiO₂/Sn O₂ hybrid electron transport layer to obtain a more uniform perovskite layer with excellent photoelectric properties,and achieved a high efficiency of 20.10%,which is improved by 20.8%,compared with the devices based on the pristine TiO₂ electron transport layer.The related mechanism research results show that the IL-TiO₂/Sn O₂ hybrid electron transport layer reduces the defect state density,has a faster electron extraction and transport process,and significantly inhibits the carrier interface recombination reaction.Compared with the device based on TiO₂ and IL-TiO₂ electron transport layer,The PSC device based on IL-TiO₂/Sn O₂ hybrid electron transport layer has obtained the best photoelectric performance.2.New ionic liquid electron transport layer and high-efficiency composite electron transport layer.First of all,to solve the problems of high preparation temperature and complicated process in the traditional electron transport layer,we developed 1-carboxymethyl-3-methylimidazole dihydrogen phosphate ionic liquid material,which can be obtained ionic liquid electron transport layer directly by spinning at room temperature.Through optimization of the preparation process conditions,a dense and uniform ionic liquid electron transport layer was obtained,and a high-quality perovskite light-absorbing layer was prepared based on the ionic liquid electron transport layer.The ionic liquid electron transport layer achieved a high efficiency of 13.37%.Secondly,we further constructed IL/Sn O₂ hybrid electron transport layer,and achieved a high efficiency of19.06%,which is improved by 42.6%.Related research results show that IL/Sn O₂ hybrid electron transport layer effectively accelerates electron extraction and electron transport,and significantly inhibits carrier recombination.Based on the IL/Sn O₂ hybrid electron transport layer,a more uniform and high-quality perovskite film is obtained,which effectively improves the stability,light absorption and fluorescence properties of the perovskite film,thereby obtaining excellent photoelectric properties.