摘要/Abstract

共轭高分子材料由于其优异的光电性能和可溶液加工等特性在有机光电器件中具有重要应用.本工作采用Stille偶联和Suzuki聚合反应，合成了两个由经典发光基元苯乙烯片段和共轭吸电子结构基元苯并噻二唑共聚的高分子材料聚（1，2-双（2，5-双（异辛氧基）亚苯基亚乙烯基-2，1，3-苯并噻二唑））（PVBT）和聚（1，2-双（2，5-双（正辛氧基）亚苯基亚乙烯基-2，1，3-苯并噻二唑））（nPVBT）.通过凝胶渗透色谱（GPC）、元素分析及差式扫描量热法（DSC）对PVBT和nPVBT两种高分子材料的结构及热稳定性进行表征，结果表明它们均具有良好的热稳定性，分解温度约380℃.由于烷氧基链的存在，两个材料具有良好的溶解性及成膜加工性.PVBT和nPVBT均表现出优异的发光特性，最大发射波长在590~605 nm范围，溶液下荧光量子产率为23%~35%，固态薄膜下量子产率为12%~20%.以这两个高分子材料薄膜作为活性层，所制备的顶栅-底接触型有机场效应晶体管器件显示出典型的p型电荷传输性能，空穴迁移率可达1.1×10^-4 cm²·V^-1·s^-1，开关比为10³~10⁴.本研究为发展高性能光电集成高分子材料提供了新思路，有望推动有机光电集成器件的研究.
关键词: 苯乙烯, 苯并噻二唑, 高发光, 场效应性能
Conjugated polymer materials with good photoelectric performance, solution processing ability and flexibility are widely used as active layers in optoelectronic devices. Here, using Stille and Suzuki coupling reactions, we designed and synthesized two new conjugated polymers, poly(1,2-bis(2,5-bis(iso-octyloxy)phenylenevinylene-2,1,3-benzothiadiazole)) (PVBT) and poly(1,2-bis(2,5-bis(n-octyloxy)phenylenevinylene-2,1,3-benzothiadiazole)) (nPVBT), which contain structural element styrene fragments and an conjugated unit benzothiadiazole. Styrene fragments are conducive to luminescent properties of materials, such as phenylenevinylene (PPV) derivatives, while benzothiadiazole unit is electron withdrawing, and matches with many structural units of a donor. The conjugated polymers were characterized by gel permeation chromatography (GPC), elemental analysis and differential scanning calorimetry (DSC). The results indicate that each of these two polymers has good thermal stability. Their melting points were around 240~250℃ and decomposition temperatures around 380℃. Due to the presence of the structural alkoxy chains, these two polymers exhibit good solubility, which is conducive to solution-processed film formation. PVBT and nPVBT have strong fluorescence characters with maximum emission in the range of 590~605 nm. The photoluminescence quantum yield of these two polymers in dichloromethane solution (1×10^-5 mol·L^-1) is 23%~35%, and 12%~20% in solid films, which are annealed at 180℃ for 10 min. Due to benzothiadiazole's regulation of molecular energy levels, the highest occupied molecular orbital (HOMO) energy level of PVBT and nPVBT were modulated to be -5.73 and -5.61 eV, and the lowest unoccupied molecular orbital (LUMO) energy level were -3.37 and -3.32 eV, respectively. Typical p-type transporting property was determined by using PVBT and nPVBT films as active layers in organic field effect transistors. Because of the improved conjugation of the skeleton structures and the close packing between benzothiadiazole of main chains, these two conjugated polymers both exhibit efficient charge transport characteristics with saturation hole carrier mobility is up to 1.1×10^-4 cm²·V^-1·s^-1 and high switching on/off ratio of 10³~10⁴. This work provides new insight into the development of high-performance optoelectronic conjugated polymer materials and sheds light on the research of organic optoelectronic integrated devices.
Key words: styrene, benzothiadiazole, strong emission, field-effect transporting property


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