Pssna-assisted Transfer Printing Technique And Its Application Research In Organic Solar Cells

In recent years,organic solar cells have been progressed rapidly and show great potential for power generation applications.It is important to prepare high-quality active layers for obtaining high-performance organic solar cells.Traditional methods(such as spin-coating,doctor blading,screen printing,etc.)for active layer film preparation are often restricted due to the influence of solvents on adjacent layers and the difficulty of processing on curved surfaces.The transfer printing technique can effectively overcome these problems by preparing the film on an intermediate substrate followed by transfer printing it on the target substrate.The adhesion between the film and substrates is the key to the successful transfer of films.In general,surface energy,interfacial Van der Waals force,hydrogen bonds,interaction at interfaces can affect the transfer printing process.In this thesis,a layer of poly(sodium-4-styrene sulfonate)(PSSNa)is introduced to assist the active layer exfoliation,and to engineer an interface interaction to assist the film transfer printing.This transfer printing method is further studied for its application in organic solar cells.First of all,this research explores the method of PSSNa-assisted transfer printing organic active layers.The large area of active layer(16 cm~2)is completely exfoliated from the substrate due to the hydrosoluble property of PSSNa.When the active layer contacts the surface with electron transport layer(PEI-Zn),spontaneous water repulsion appears.It is found that spontaneous water repulsion also occurs when the active layers exfoliated with PSS~-contact other surfaces(such as Zn O,PEI and PEIE).This is resulted from the electrostatic interaction between the two surfaces.This interaction promotes the adhesion between the active layer and the substrate,and also makes the transfer printing of active layers more convenient.With this method,the active layer can be transferred onto various substrates.Furthermore,based on the PSSNa-assisted transfer printing method,organic solar cells are fabricated on flat,flexible and curved substrates respectively,and their performances are studied.The performance of the solar cell prepared on the flat substrate is comparable to the one prepared by the traditional spin-coating method,with a power conversion efficiency of 14.0%.The solar cell fabricated on the flexible substrate reaches an efficiency of 11.4%,and its mechanical flexibility is well.The efficiency of the large-area(10.2 cm~2)flexible solar cell reaches 12.6%.The efficiency of the solar cell fabricated on the curved substrate reaches 10.8%.This demonstrates the great applicability of the transfer printing method.