Reasrch On The Photoelectric Properties Of SnO₂ Electron Transport Layer Modified By Ytterbium

Perovskite solar cells have attracted wide attention due to their high conversion efficiency and low preparation cost.Compared with organic semiconductor materials,perovskite materials have higher absorption coefficient,more suitable bandgap width and longer carrier diffusion length.In recent years,its efficiency has rapidly increased to 22.3%,which also brings the possibility of future development in the field of photovoltaic.But at this stage of perovskite solar cells on the surrounding environment in the process of preparation technology demand is higher,the change of temperature and humidity will be on the performance of the perovskite solar cells have a significant impact,the vast majority of research work are also limited in the glove box,too sensitive to the environment would be tantamount to increase the cost of the mass production,hindered the process of its commercialization.Therefore,the development and research of perovskite solar cell technology in atmospheric environment has undoubtedly become a new trend.SnO₂-based perovskite solar cells（PSCs）were firstly studied in atmospheric environment.Through the characterization and statistics of the device efficiency,the spinning coating process of the next step method in atmospheric environment was successfully explored（perovskite precursor concentration,drip anti-solvent time,and annealing time of perovskite film）.With ytterbium chloride as ytterbium source,rare earth elements were successfully doped into the electron transport layer of perovskite solar cell by hydrothermal synthesis method.The results show that the rare earth elements effectively reduce the transmission resistance of the electron transport layer,accelerate the quenching of excitons,and greatly improve the electron transport capacity without affecting the crystallization of SnO₂.At the same time,the surface roughness of perovskite film is reduced effectively,and the direct contact between layers is better.The filling factor of the device was increased from67.87%to 73.35%,and the photoelectric conversion efficiency was increased from14.05%to 16.12%,and the hysteresis was significantly improved,which effectively improved the filling factor of the device and other photoelectric performance.Then in the air stability and thermal stability test,the modified device can still maintain the photoelectric conversion efficiency of more than 80%,while the photoelectric conversion efficiency of the unmodified device decreases to about 40%.In the second part of the experiment,ytterbium ions were introduced into SnO₂hydrocolloid solution.By improving the surface roughness of the electron transport layer,the electron extraction and transmission capacity of the electron transport layer were improved,and the SnO₂ hydrocolloid perovskite solar cell was modified.The results show that a small amount of ytterbium-modified SnO₂ hydrocolloid thin film is more flat,which is conducive to the formation of perovskite thin film,and the defect state between the electron transport layer and perovskite layer is also less,so the modified SnO₂ hydrocolloid perovskite solar cell has higher photoelectric conversion efficiency and better stability.According to the volt-ampere characteristic curve,the open circuit voltage of the modified device increased from0.97v to 1.03v,and the photoelectric conversion efficiency increased from 14.30%to 16.22%.Then the electron transfer process in the device was tested by fluorescence spectrum and space charge limiting current,and the mechanism was analyzed.