Synthesis And Research Of Amine-functionalized Organic Small Molecule Materials Used As Cathode Interface Layer In Organic Solar Cells

Recently, Organic Solar Cells(OSCs) have become a research hotspot due to their advantages of simple preparation, light, flexible, etc. To improve efficiency of the cell, researchers conducted intensive studies in synthesis of new donor materials and acceptor materials, morphology adjusting of active layer, interface modification, and other aspects.This thesis describes the basic development of OSCs first, including the development process of device structures, the basic principles, factors affecting the performance of OSCs, and so on. In addition, the role of the interface layer in OSCs and the development situation of the organic interface materials are introduced in detail. In this paper, in-depth studies about advantage and disadvantage of the current organic interface materials are made, mainly including the following two aspects:1, A series of neutral amine-based fluorene oligomers were synthesized through Suzuki coupling reactions. By introducing additional carboxylic acid ester, carboxylic acid, and potassium carboxylate, which possess different hydrophilic, as pendant group, respectively, interface materials named TFN2 COOtBu, TFN2 COOH, and TFN2 COOK with different hydrophilic were obtained. All inverted devices with these materials as electron transporting layer(ETL) achieved PCEs exceeding 8%. Among them, TFN2 COOH get a balance between hydrophilic and hydrophobic. When used as ETL in inverted devices, its solubility made sure it not being eroded, and the proper hydrophobic of it was beneficial for the spread out of the photoactive layer. At last, we realized high PCE of 8.94% and simultaneously solved the solvent erosion problem.2, A series of small molecule electrolyte materials with different cations were synthesized through Suzuki coupling reactions, which were named TFN2 COOtBu, TFN2 COOH, and TFN2 COOK. All of the conventional devices using them as ETL achieved PCEs exceeding 8%. When they were used in inverted devices, relatively low PCEs were obtained. But after adjunction of additional bias voltage for a few seconds, the open-circuit voltage and fill factor of the battery increased obviously. Moreover, the higher pre-bias shortened the saturation time and got higher saturated open-circuit voltage. Although the materials with different cations have different device performances, we can conclude that ions-moving was existent when additional bias voltage was added to.