Study On The Vertical Phase Separation Morphology Of The Active Layer Of Polymer Solar Cells And The Performance Of Photovoltaic Devices

Traditional inorganic solar cells represented by monocrystalline silicon and gallium arsenide have achieved high photoelectric conversion efficiency,but their production and raw material costs remain high,and the production process is complicated,which limits their large-scale application.To solve this problem,scientists have focused on low-cost third generation solar cell technology.Among them,the production process of polymer solar cells does not require expensive coating equipment,has a wide range of material sources,has the advantages of solution processing,can produce large-area flexible devices,etc.Polymer solar cell has attracted widespread attention in the academic and industrial fields in recent years.The main work of this paper is as follows:1.Briefly introduced the classification and development background of organic solar cells,and elaborated the working mechanism and characterization parameters of polymer solar cells.The preparation process of polymer solar cell devices and the method of controlling the morphology of the active layer were introduced.2.Using benzodithiophene-benzothiadiazole copolymers PBDTT-DFDTBT（P3）and PC₇₁BM as polymer donor and acceptor materials,regular and inverted devices were fabricated.Tetrahydrofuran solvent annealing was systematically studied about vertical separation of the active layer and the effect of the photovoltaic device performance.The regular device fumigated with THF solvent has improved photovoltaic performance,while the inverted device has the opposite effect.It has been found that THF solvent annealing causes donors and acceptors to agglomerate toward the top and bottom in the vertical direction,optimizing the size of donor-acceptor phase separation and increasing the purity of the phase region.For the regular device,the charge transfer state binding energy required for exciton separation can be reduced,the defects in the active layer can be reduced,and the dissociation efficiency of the exciton can be improved.Trap-induced carrier recombination in inverted device due to the vertical phase separation of the acceptor and doner,its short-circuit current and fill factor decreased.Polymer donor J52 and n-type non-fullerene receptor ITIC,ITIC-Th were selected as the active layer material to fabricate a high-efficiency polymer solar cell device.By adjusting the proportion of the acceptor,different solvents were selected,and thermal annealing treatment,the device performance was optimized.The photovoltaic parameters based on the J52:ITIC system cell:Jsc reached 16.77 mA/cm2,the corresponding FF was 64.6%,and the PCE reached 8.54%.Based on J52:ITIC-Th system photovoltaic parameters:Jsc reached 17.15mA/cm2,the corresponding FF was65.2%,and the PCE reached 8.77%.