The introduction of optoelectronically inactive long chain alkyl substituents commonly used to improve the solubility and film processing can inhibit intermolecular charge transfer in organic semiconductors. Therefore, to decrease the inactive alkyl substituents is important for next generation semiconductors. Herein, we designed and synthesized two perylene bisimide derivatives ( PBI1 and PBI2) and investigated the effect of ortho-methylphenyoxyl substituent in bay area on molecular conformation and packing modes in the solid-state. The single crystal analysis confirmed that introduction of CH3 could significantly affect the molecular conformation of PBI, leading to cross-style four phenoxyl groups. The steric hindrance of CH3 inhibited the intermolecular π-π stacking, increased the solubility and enhanced the film-forming characters. The results show that CH3 at the key positions of π-conjugated skeleton could effectively regulate the molecular aggregation. The strategy provides an excellent method to enhance the film processing and decrease the optoelectronic inactive alkyl substituents, therefore an important step forward for the design of new optoelectronic materials.%设计并合成了2种苝二酰亚胺分子PBI1和PBI2,研究了bay区的苯氧基团邻位甲基取代对分子构型及分子聚集的影响.通过对单晶结构的分析,发现邻位甲基的引入明显影响苝二酰亚胺分子构型,使得4个苯氧基呈中心对称分布.由于甲基的空间位阻效应,有效地减弱了分子间π-π相互作用,从而提高了分子的溶解性与溶液加工成膜性.研究结果表明,在π共轭分子结构中的关键位置引入小的甲基取代基能够显著调控分子的聚集行为,有效减少光电材料分子中非光电活性(增溶性基团)的含量,对光电材料分子的设计合成具有重要的指导意义.
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