| In the photovoltaic devices and optical detectors,perovskite materials have attracted a lot attention in recent years because of their low exciton binding energy,high absorption coefficient and long carrier diffusion length.Up to now,with the upgrading of materials,the progress of fabrication methods and device structures,the performance of photovoltaic devices has been rapidly developed and the conversion efficiency of photovoltaic devices has exceeded 23%.This thesis is based on the bulk heterojunction structure fabricated by perovskite material as active layer.The influence of the device structure innovation and thin film ions regulation on the photoelectric performance of the device is also studied in this thesis.Firstly,a perovskite solar cell with energy band gradient was prepared.The device structure is ITO/NiO/MAPbI3-xBrx（x=0,1,2 or3）/ETL(ICBA,PCBM or ICBA:PCBM/Al.It is characterized by a horizontal series arrangement of subcell cells with different bandgaps,in which incident photons with different energies are sequentially captured by four different subcell units.The advantage of this device structure is to minimize thermodynamic loss and improve the open-circuit voltage of perovskite solar cells.Based on this structure,by adjusting the optical pathway of incident light,the photons from high to low energy are captured by different bandgap subcell units,in which the subcell unit MAPbI3-x-x Brx（x=0,1,2 or 3）.The open-circuit voltage values generated by four sub-cell units are from 1.15 V to 1.54 V,respectively.The total open-circuit voltage of the four series sub-batteries is 5.3 V.This new structure of perovskite solar cells greatly improves the efficiency of energy conversion.Efficiency increased from 18%of pure MAPbI3 devices to 21.3%.Then,a simple one-step brush-coating method is proposed to fabricate perovskite(CH3NH3PbI2.61Br0.39)optical detector.This method can change the ion composition of perovskite film and optimize the morphology of perovskite film.And it has the following advantages:The brush materials have selective adhension on ions in the solution,which can be used for ion regulation of perovskite film.Because of the use of brush-coating technology,the excess PbI2 in perovskite film can passivate the defects in the crystal boundary and thus suppress the dark current.According to the surplus amount of the ions in the brushing process,the proper proportion of each component can be advantageously determined in the original solution,so that the content of the excess ion can be optimized in advance.As fabricated perovskite thin films have higher quality and less grain boundary,which makes the perovskite materials more difficult to degrade.Compared with the perovskite photodetectors fabricated by conventional spin-coating process,the results show that the dark current and detection rate of the photodetectors are 1.51×10-1212 A and 7.69×10122 Jones respectively.To sum up,the perovskite photovoltaic/photodetector prepared in this study have excellent device performance,providing a new possibility for the commercia lization of the perovskite photovoltaic/photodetector. |
