Design And Synthesis Of Ion Salt Interface Materials For Novel Solar Cells

Recently,organic and dye-sensitized solar cells have been attracting extensive interest in the field of organic optoelectronics due to their advantages of low cost,simple preparation process.Commonly,organic materials show excellent flexibility and controllable chemical structure with great prospects in the photovoltaic industry.Organic solar cells have achieved many advances in the past few decades,and the state of art power conversion efficiency（PCE）is exceeded 17%by the design of new materials and continuous upgrading of preparation processes,which is compared to these commercial silicon solar cells.In this regard,the interface plays a vital role in the transport and collection of carriers.By introducing new interfacial materials with the function of the interface modification,the improved efficiencies are gotten.In the meanwhile,these interfacial materials are also significant to develop low-cost and large-scale organic solar cells with novel functional materials,which will partly solve some issues on energy and environment.In this paper,the novel cathode interface modification materials of organic solar cells were designed and synthesized.Two non-conjugated small molecular materials with branched structures were prepared and soluble in the common organic solvents,which is suitable for solution-processed devices.Furthermore,organic solar cells based on celluloses and their derivatives are also employed as interfacial materials for the modification of cathode electrode,which provides the chance for green electronics.Two novel non-conjugated small molecular zwitterions are designed and synthesized,named 4-（N-methylpiperidinyl）propy sulfonate（MPPS）and 4-（N-methylpiperidine）butyl sulfonate（MPBS）which is used as the cathode interface of organic solar cells.Their chemical structures,photochemical and photophysical properties were studied systematically.The results show these synthesized zwitterions can be used as cathode interface layer for organic solar cells.Organic solar cell devices were fabricated with the structures of ITO/PEDOT:PSS/PBDB-T:ITIC-M/MPPS/Al,ITO/PEDOT:PSS/PBDB-T:ITIC-M/MPBS/Al,and ITO/PEDOT:PSS/PBDB-T:ITIC-M/Ca/Al.The results are found the best PCEs based on them are 9.020%,8.316%,and7.489%,respectively.In the meantime,the relationship between molecular structure and properties were also studied.The cells based on N719 dye as dyes were fabricated and the best one of power conversion efficiency is reached 8.11%(V_OC=0.74V,J_SC=16.12 mA/cm²,FF=67.98%).Importantly,the introduction of cellulose conductive film effectively solves the problem of the traditional dye-sensitized solar cells has many surface defects and is not suitable for flexibility,which is of great significance for the development of flexible dye-sensitized solar cells.