Study On The Materials Designing Of Charge Transfer Layer And Device Performance Optimization For Perovskite Solar Cells

In recent years,perovskite solar cells have become one of the most promising photovoltaic technologies due to their wide spectral absorption,long carrier transmission distance,simple preparation process and low-cost fabrication.Since it was found in 2009,the development of perovskite solar cells has exceeded our expectations,with an average increase of about 2%of the power conversion efficiency annually.However,there are many issues of perovskite solar cell devices prepared by common methods,such as small grain size of the perovskite layer,and large amount of crystal defects.These defects are ultimately manifested in the relatively effect on the separation of electron-hole pairs and the charge transfer in the active layer,which results in low power conversion efficiency and stability of the device.In addition,the materials and processing technology of the charge transfer layer also affect the efficiency and stability of the devices.In view of the above problems,this study mainly focuses on the material design,processing technology of charge transfer layer and perovskite layer optimization.The specific work includes following parts:?1?The morphology control of spiro-OMeTAD layer was studied by solvent vapor annealing method,and the performance of CH₃NH₃PbI₃ based perovskite solar devices was significantly improved by optimizing the relevant parameters.It was found that a smoother spiro-OMeTAD layer could be obtained by solvent vapor annealing process,and the interfaces between perovskite/spiro-OMeTAD and spiro-OMeTAD/Au was more closely contacted.The interfacial contact between the layers of device was improved,which enhanced the charge transfer properties,thus significantly improved the performance of the device.The average photoelectric conversion efficiency increased from 14.62%to 16.73%compared with control group.?2?The performance improvement of perovskite solar cells by alcohol based vapor annealing processed PEDOT:PSS layer was studied.Our results indicated that the hole conductivity of PEDOT:PSS layer was improved,owning to the enhanced phase separation between PEDOT and PSS.Meanwhile,the device fabricated by this method had small hysteresis.The results suggest that the alcohol vapor annealing is a simple and effective method to develop high performance inverted perovskite solar cells.?3?DMF and GBL were investigated as processing solvents for fabricating?BA?₂?MA?₃Pb₄I₁₃ based two-dimensional?2D?perovskite.By utilizing the precursor solvent with slow evaporation rate,the crystallization for the growth process of perovskite was retarded,which enhanced the quality of perovskite film.Caused by the improved crystallinity,the photon trapping property was improved,as well as the production of excitons.As a result,the GBL processed device exhibited the highest efficiency of 11.65%with stable power output and negligible hysteresis.It is concluded that GBL based precursor solvent is beneficial for 2D perovskite processing,which resulted in higher performance 2D devices.?4?A high power conversion efficiency?PCE?and long-term stability of Ruddlesden–Popper type 2D perovskite solar cells were explored.Two-dimensional perovskite solar cells were fabricated by using non fullerene acceptor as electron transport materials.The results indicate that ITIC-Th is an effective alternative material for developing 2D perovskite solar cells.