Organic-Inorganic Hybrid Solar Cells With ZnO/Polymer Structure: Study Of Interface Modification And Charge Recombination Kinetics

Organic-inorganic hybrid solar cells,which is a new type of solar cells,gain the advantages of high theoretical efficiency,good stability and low cost,but there are still some shortcomings and low power conversion efficiency.Three aspects of interface modification,preparation technology optimization and cell structure were investigated in this paper in order to optimize the cell performance:1)By introducing two small organic molecules into the ZnO/P3 HT interface,the properties of heterojunction interface were modified.The organic-inorganic heterojunction interface of hybrid solar cells has a decisive effect on the cell performance.The compatibility between the inorganic and organic materials was improved,and excitons separation efficiency was accelerated by employing the organic molecules.The power conversion efficiency of hybrid solar cells was enhanced from 0.23% to 1.41%.Additionally,the interface charge transfer and recombination mechanisms were investigated by cyclic voltammetry and electrochemical impedance spectroscopy.2)The influence of preparation technology on cell performance was explored systematically.In brief,the density of ZnO nanorods was regulated using different concentrations of sol-gel precursors and length of ZnO nanorods was controlled with various hydrothermal time;then by different thermal treatment temperature,the stacking of polymer chains was adjusted;and hole transporting property of PEDOT:PSS was changed using different spin-coating layers.Through the systematic technical improvement,the cell devices performance was enhanced to 1.44% gradually.The charge separation,transport,and recombination kinetics mechanisms were analysed with different electrochemical and optical measurements.3)The difference between layered structure and blended structure of ZnO-based hybrid solar cells was compared in detail for the first time in this study with the P3 HT as electron donor and spiro-OMeTAD as hole transport material.PEDOT:PSS is a common hole transport material used in hybrid solar cells.Meanwhile,it owns a low hole mobility and can absorb moisture,resulting in poor cell performance.Consequently,spiro-OMeTAD,which was introduced into the cell devices as hole transport material to replace PEDOT:PSS,could assist the P3 HT to transfer holes.Power conversion efficiency of cell devces was improved from 0.53%(layered structure: FTO/ZnO/P3HT/spiro-OMeTAD/Cu)to 1.24%(blended structure: FTO/ZnO/P3HT:spiro-OMeTAD/Cu).Eventually,the performance of hybrid solar cells was improved through the research of the above three aspects,which also provided experimental basis and theoretical data for further research.