Design Of TPE-based Molecules And Their Interfacial Modification And Mechanoluminescence Behaviours

In the past decades,organic semiconductor materials have achieved numerous breakthroughs and been widely applied in organic photovoltaic solar cell,perovskite solar cell,organic field effect transistor,organic light-emitting diode,biological imaging and so on.Despite the performance of materials depends heavily on the intrinsic properties of compounds,the molecular packing in the aggregation state also has a great influence on the materials performance to a large extent.Generally,organic semiconductor materials are often used in the aggregation state during the practical application process.Numerous organic semiconductor materials suffer in the issues of performance degradation due to the adverse molecular aggregation.Aggregation-induced Emission(AIE)materials can not only effectively address the above issues but also utilize the aggregation process.Tetraphenylethylene(TPE)is a most widely-used AIE building block,for its simple molecular structure,flexible modification,easily available synthesis and remarkable AIE effect.By combining TPE with the other fields,the issues of adverse aggregation might be effectively solved.Additionally,TPE unit possess a special packing mode,which plays an important role in exploring the configuration relationship among the molecular structure,molecular packing and material properties.Triphenylamine(TPA),a commonly-used building unit in organic photoelectric materials,possesses a similar twisted configuration and can be applied to solve the problem problem of performance degradation caused by the molecular aggregation.And it is also beneficial to study the configuration relationship between material performance has important significance.The main work of this thesis is constituted by the following two parts.In the first part,the alcohol-soluble AIE-active materials containing TPE block were designed,synthesized and applied as cathode interlayer in the high-performance planar p-i-n perovskite solar cells.Additionally,the influence of TPE derivatives on device performance were also deeply investigated.In the second part,a series of TPE derivatives and triphenylamine(TPA)derivatives with twisted configuration were designed and synthesized.These TPE or TPA derivatives exhibt different mechanoluminescence(ML)effects,and the configuration relationship among molecular configuration,solid packing and ML performance are explored deeply.In chapter 1,the mechanism of the AIE effect based on TPE unit and the practical application of TPE derivatives in organic opto-electric materials are introduced.The author emphasized on the design concept and practical application of TPE as a building block in various fields.Finally,the research on the relationship among the molecular configuration,molecular packing model and performance is vitally important,and desigingn ideas of this thesis were presented.In chapter 2,an AIE-active polymer(PTN-Br)containing tetraphenylethylene(TPE)backbone and quaternary ammonium salt side chains,was designed and utilized as the cathode interfacial materials to fabricate high-performance organic and inorganic hybrid perovskite solar cells and grain boundaries interfacial materials to prepare high-PCE lead-free perovskite solar cells.The influence of PTN-Br on device performance was also investigated.Careful investigations demonstrate that,thanks to the special molecular packing of TPE unit in solid state,PTN-Br can effectively improve the UV stability of PVSCs,for its suitable absorption in UV region and intense emission in visable region.In chapter 3,two TPE derivatives,namely TPE-NO and TPE-NE,with different polarity side chains were designed,synthesized and applied as the cathode interfacial materials of organic and inorganic hybrid perovskite solar cells,to reveal the effects of different polarity side chains on the performance of perovskite solar cell devices.The inverted perovskite solar cell with perovskite as the active layer,PCBM as the electron transport layer and silver electrode as the cathode,possesses power conversion efficiency of 17.33%,which exceed that of the reference one(16.64%).The influence of different side chains on the PCE and stability of PVSCs was also investigated deeply.In chapter 4,TPE-oMe,TPE-2oMe,TPE-2oMe-EZ and TPE-3oMe containing different amounts of methoxy groups were designed and synthesized.The four TPE derivatives possess different ML behaviours: TPE-2oMe and TPE-2oMe-EZ could emit intense fluorescence under the mechanical stimulation,while TPE-oMe exhibts weak ML emission under the conditions,and TPE-3oMe was ML-inactive.Careful investigation of the single crystal structures demonstrated that the asymmetric arrangement and strong intermolecular interaction mainly contribute to the strong ML emission.In chapter 5,TPA unit possesses a distorted spatial configuration,which can effectively inhibit the decrease of fluorescence intensity caused by the ?-? stacking effect among solid molecules.Therefore,similar to TPE unit,TPA unit applied in the field of electroluminescence can also overcome the adverse influence of weak solid fluorescence of organic materials on their mechanoluminescence behaviour.TPA-CHO,and TPA-CHO-2F,TPA-CHO-2Cl and TPA-CHO-2Br containing different halogens were designed and synthesized.In comparasion with TPA-CHO(ML-inactve),TPA-CHO-2F,TPA-CHO-2Cl and TPA-CHO-2Br all exhibited intense ML emission.The theoretical calculation results based on the crystal structure demonstrated that the electronic structure of TPA-CHO was changed after the introduction of halogen atoms,resulting in their tight molecular packing,which mainly contribute to their ML performance.In chapter 6,three TPE derivatives were obtained by introducing fluorine atoms into TPE-2oMe and TPE-2oMe-EZ.Regardless of thier similar structure,their electronic structures were largely changed.And the different electronic structures could lead to different molecular dipole moment and molecular packing in solid state.Z-BFBM-TPE and BFBM-TPE with larger dipole moment and stronger intermolecular interaction possess intense ML emission.Additionally,the intensity of ML emission is also related to their emission intensity in solid state,and Z-BFBM-TPE which possesses intense fluorescence in solid state show strong ML emission.