A Comparative Study On Organic Photovoltaic Solar Cells With Different Structures

This thesis begins from the next attitudes to explore ways to enhance the efficiency and stability for organic solar cells,namely,the solution-processed interface materials,the alteration of active layer components,single junction conventional and inverted structure.The main content of this dissertation is the following:The work function of the cathode buffer layer(CBL)enormously influences on performance of organic photovoltaics,specifically the VOC,and the performance can be achieved with ohmic contact among the buffer layer and active layer.The Hf(acac)4 and Ta-OMeare a cathode modification layer can be get ready by simply spin-coat a soluble of Hf(acac)4 and Ta-OMe on the photo-sensitive layer at room temperature without any other post-processing.The method is simple and easy,Hf(acac)4 and Ta-OMe are inserted between the A1 cathode and the active layer as a cathode modified layer in the organicBHJ solar cells.When Hf(acac)4 and Ta-OMe are utilized in lieu of the traditional Ca/Al as the cathode in a PSC,the short-circuit current can be significantly enhanced,and series resistor is also reduced synchronously.When the Hf(acac)4 and Ta-OMecathode is used in the SCs with P3HT:PCBM as the photoactive layer,the PCE measured under standard illumination conditions(AM 1.5G,100mW/cm2)is 3.89%,which is significantly higher than 2.04%of photoelectric conversion efficiency from solar cells using Ca/Al cathode under the same conditions.Organic photovoltaic solar cells belong on the light absortion of a photoactive materials,in addition depends also on the excitonseparationand charge transfer operationswhich iswith relative to the arrangement of the active layers.Thus,optimization the arrangement of active layers is an effectualapproach to raise the PCE of OPV SCs.The donorand acceptordistributions of mixture active film in OSCs are investigated to explore the mechanism and method to improve the PCE.The device based on P3HT:PC70BM and PBDB-T:PC60BM with Ta-OMe modified layer was fabricated and analyzed(with different photoactive blend based on P3HT and PC60BM contender polymer semiconductor materials).All device of PSCs as were investigated under the same conditions.The PCE of the devices with Ta-OMeconducting electrode based on P3HT:PC70BM,and PBDB-T:PC60BM,reaches 4.12%,and 5.12%,respectively,it is much higher than comparative devices with naked Al(2.37%,and 3.65%)and Ca/Al(3.25%,and 4.14%)cathodes.The device based on PBDB-T:PC60BM active layer fundamental four parameters has been improved dramatically.Solution-processable titanium(diisopropoxide)bis(2,4-pentanedionate)(TIPD)material is employed as a negative electrode interface layer in inverted non-fullerene based single polymer solar cell.The inverted mono junction device is prepared based on the electron donating and electron accepting which can form complementary absorption.The employment of the inverted structure with high-work function metal as an anode,avoiding the moisture and oxygen sensitive Ca/Al cathode electrode,effectively improved the PCE of polymer solar cells.In PBDB-T:ITIC-M blend film,PBDB-T mainly distribute in the top side,while ITIC-M dominates the bottom of the film,which is suitable in solar cells with inverted structure.Inverted solar cells with TIPD and conventional solar cells with a PEDOT:PSS have been prepared,the results show that the inverted solar cells haveattained a PCE of 8.9%,that is40%higher than 6.32%of conventional solar cells.Also,the inverted structure device avoids the vapor and oxygen sensitive Ca/Al electrode,which is benefit to the stability of solar cell.