Preparation Of Heterocyclic Structure Polyimide Film Substrate And Its Application In Solar Cells

Polyimide?PI?has important research significance in designing new types and high heat resistance.In this thesis,a series of PI films with excellent comprehensive properties were prepared by molecular design of oxazole and imidazole ring.The relationship between structure and properties was discussed and used as copper indium gallium selenide?CIGS?.The thin film solar cell substrate material was studied based on the process of Mo back electrode for CIGS solar cell on flexible high temperature resistant PI substrate.The specific research contents are as follows:1.Using 4,6-diamino-1,3biphenyldiol as raw material,a high-purity diamine monomer was synthesized by reaction.Polyamic acid?PAA?is prepared from oxazole-containing diamine monomer and dianhydride monomer?s-BPDA?;the polyamic acid was subjected to a casting method.The film was coated and subjected to high temperature imidization to prepare a polyimide film containing a oxazole ring in the main chain.The structure and properties of the monomers and polymers were characterized by 1H-NMR,FT-IR,TGA and tensile testing.The results show that BAPBBOA has the expected structure and high purity;the glass transition temperature?Tg?of the polyimide with oxazole structure in the main chain is as high as 345?;and T_5%is 595?;the tensile strength of the PI film is 295 MPa,and the elongation at break is 15 to 18%;2.Polyaniline was prepared by normal temperature polymerization of benzidine and DAPBI as diamine monomer and dianhydride monomer?s-BPDA?,and polyimide film was prepared by thermal imidization after blade coating.By testing the physicochemical data,it was concluded that the polyimide Tg containing the oxazole structure in the main chain increased as the proportion of the imidazole ring increased.When the DAPBI copolymerization ratio reached 20%,the Tg was 392?,the tensile strength was 231 MPa,the CTE was 13.7 ppm/?,and the dielectric constant was 3.21.3.Copolymerized polyimide film was prepared from s-BPDA with BAPBBOA and DAPBI as diamine monomers.The properties of the polymer were characterized by thermogravimetric analysis?TGA?and tensile testing.The results show that the copolymer film has higher thermodynamic properties and lower water absorption;when BAPBBOA:DAPBI=6:4,T_5%is 582?,Tg is 385?,tensile strength is 280MPa,water absorption is 0.5%,compared with the biphenyl type polyimide film,its heat resistance,hygroscopicity,glass transition temperature are greatly improved;the imidazole ring and the oxazole ring are introduced into the molecular structure of the polyimide,while maintaining Its excellent overall performance not only improves the water absorption of PI,but also improves the thermodynamic properties of PI separator materials.It can be used as a high temperature resistant material in microelectronics and new energy fields.4.The film obtained by BAPBBOA and s-BPDA is used as a substrate,and a molybdenum layer is deposited on the surface of the film by DC RF magnetron sputtering.A control experiment was set with the pressure as a variable,and the experimental results were tested by XRD,XRF,and SEM.The results show that the grain size of Mo film decreases with the increase of deposition pressure.The growth rate of Mo film decreases with the increase of working pressure,and the resistivity increases with the increase of working pressure.