Research On The Application Of Graphene And Molybdenum Disulfide In Perovskite Solar Cells

Perovskite solar cells(PSCs)soon become the hot research direction after it were first introduced in 2009 due to its simple preparation process.CH3NH3 Pb I3 become the most frequently used organic-inorganic hybrid perovskite active layer material for its unique characteristics,such as high extinction coefficient,high carrier transport rate and long transmission distance.And the power conversion efficiency(PCE)records of PSCs based on CH3NH3 Pb I3 are constantly being refreshed in recent years.However,there are still some problems such as poor device stability,low open circuit voltage and obvious hysteresis effect.Therefore,how to further improve the device performance and reduce the cost of preparation has become the research focus of perovskite solar cells.In this dissertation,we focus on reducing the manufacturing costs and optimizing the cell structure.The graphene derivatives and molybdenum disulfide(Mo S2)are applied to preparing perovskite solar cell devices with high efficient and stable iodine PSCs are obtained.In addition,the preparation process and performance of bromine-doped active layer PSCs devices are also studied and bromine-doped perovskite solar cells with high voltage are available.In the experiment,the graphene oxide(GO)is used to doping the PCBM and the the PSCs devices with GO/PCBM composite electron transport layer is prepared.Compared with the pure PCBM electron transport layer device,the PCE of device based on GO/PCBM composite as electron transport layer increased by 24.38%.Mo S2 is inserted between the electron transport layer and the metal electrode as a modification layer by vacuum thermal deposition.The open circuit current density(Jsc)and open circuit voltage(Voc)of the optimized device are 25.893 m A / cm2 and 0.961 V,respectively.The fill factor is as high as 68.43% and the conversion efficiency is improved to 17.08%.The result also indicates that the existence of Mo S2 modified layer is beneficial to the protection of perovskite film and the stability of the device of the cell is obviously improved.Furthermore,the external quantum efficiency of the device has also been improved.It is noteworthy that Mo S2 applied as a modified layer improves the energy level matching and promotes the transmission of electrons between the interfaces due to the decrease of the energy barrier.Moreover,the Mo S2 modification layer also serves as a hole-blocking layer and reduces the recombination rate of carriers at the interface.The preparation process of halogen PSCs with different doping ratio of bromine is also explored.The results show that the ideal high voltage solar cell device can be obtained when the ratio of bromine doping is 1.Therefore,the preparation process of CH3NH3 Pb I2Br cell device was further optimized and the perovskite solar cell device with open circuit voltage of 1.046 V was successfully prepared.In addition,bromine doping enhances the absorptive capacity of the device to the visible light in the 350~400 nm band.However,the larger the bromine doping ratio is,the narrower the total absorption range of the PSCs is.