苝酰二亚胺衍生物的电子输运性质的第一性原理研究

The first-principles investigation of the electronic transport of PTCDIs

利用密度泛函理论与非平衡格林函数的第一性原理方法,从理论上研究苝酰二亚胺衍生物PTCDI-[CH2]n(n=0,2,4,6)分子体系的电子输运性质.结果表明:所有的分子结体系结构中都出现了负微分电阻现象,体系的电子输运性质取决于体系中分子的长度.随着CH2数目的增加,分子的长度相应增加,体系的电导呈指数减少;当n≥2时,分子结呈现整流特性;当n=6时,分子结在±2.1 V时整流比高达72.6;这种整流现象归因于分子的非对称结构.

The electronic transport properties of PTCDI-n（n=0,2,4,6） molecular junctions with different molecular lengths were theoretically investigated via the first-principles density functional theory and non-equilibrium Green＇s function method.Our results showed that the electronic transport properties depend on molecular lengths.The equilibrium conductance of the probed systems decreased exponentially with the increasing length of molecule.With n≥2,rectifying effect had been found.In n=6 case,a significant rectification ratio of 72.6 was achieved at the bias of ±2.1 V in our probed voltage range.The rectification effect resulted from asymmetric molecular structures.Negative differential resistance effect happened in all probe systems.