Synthesis And Characterization Of Chlorine-Bearing Conjugated Polymers And Azaacenes

In this dissertation, Suzuki and Stille coupling reactions have been developed to introduce chlorine atoms onto the backbone of conjugated polymers for the first time. The effects of chlorine on the optical and electrochemical performance of the conjugated polymers have been well studied, and these chlorine-bearing conjugated polymers could be used as light-emitting materials. Additionally, azaacenes were obtained throuth the condensation between aromatic ketone and aromatic amine. The effects of different substituent on the optical and electrochemical performance of the materials have been well studied, and these conjugated small molecules were used as photovoltaic materials for the first time. The detailed results were briefly described as below:1) High selectivity and yield from aryl-aryl coupling reactions between chlorine-containing aromatic bromides and organoboron or organotin reagents were obtained. The variable reaction selectivity between the bromine and chlorine mainly depends on the electronic effects of the aromatic substrates. The reactivity of the chlorine can be completely restrained by employing the optimized Palladium catalysts. The chlorine-containing conjugated polymers were prepared through the Suzuki and Stille couplings by using the optimized reaction conditions for the first time and the molecules had high molecularweight, good solubility and thermostability, indicating that the optimized Suzuki and Stille coupling reaction could be the commonly method to prepare the chlorine-containing materials, especially for the polymers.2) The calculation based on density functional theory (DFT) proved that the chlorine atoms twisted the backbone of the copolymers, reduced the conjugation, restrained the intramolecular charge transfer, causing the blue-shifted absorption spectra. The large Stokes shift and low self-absorption could be attributed to the large steric hindrance of chlorine atoms. The HOMO and LUMO levels could be modified individually, which could help the optimization for the photoelectric properties and the performace of the devices. These chlorine-bearing copolymers exhibited variable LUMO energy levels after the introduction of chlorine onto the backbone of the polymers, deeper LUMO for the quinoxaline-based polymers and higher one for the thiadiazole-based polymers. When extended the donor units, the resulted copolymers exhibited higher HOMO, narrower bandgap and wider absorption. For the PLEDs of the polymers, chlorine atoms caused the blue-shifted EL spectra comparing with the none-chlorine polymers, and good for the Brightness and EQE of the devices. Finally, emission centre at702nm,715nm,729nm and756nm were obtained based on the simple single layer devices, which indicating the chlorine-containing polymers were competitive candidates for NIR light-emitting materials.3) A series of azaacenes were obtained throuh the condensation between aromatic ketone and aromatic amine, which is efficiently and simply, and the molecules had good solubility and thermostability. The calculation based on density functional theory (DFT) proved that the backbone of the compounds had an excellent planar structure, which could be tuned by introduction the thiophene and tertbutyl onto the main structure, inducing weak red shift of the solid absorption, and the results of XRD confirmed the above conclusions. When extended the thiophene units, the resulted copolymers exhibited higher HOMO levels, narrower bandgaps and wider absorptions. These materials were used as electron donor materials and blended with the PCBM as electron acceptor to prepare the organic solar cells by solution processing. The BB2T based device showed a performance:power conversion efficiency (PCE)=1.16%with short circuit current (Jsc)=2.32mA/cm2, open circuit voltage (Voc)=0.91V and fill fact (FF)=33.9%. The B2AT based device showed a performance:power conversion efficiency (PCE)=1.60%with short circuit current (Jsc)= 5.30mA/cm2, open circuit voltage (Voc)=0.82V and fill fact (FF)-37.5%. The B2A2T based device showed a performance:power conversion efficiency (PCE)=1.36%with short circuit current (Jsc)=2.66mA/cm2, open circuit voltage (Voc)=0-88V and fill fact (FF)=36.1%, which indicating the azaacenes were competitive candidates for photovoltaic materials.