(CH_3)_2和(NH_2)_2基团修饰的齐聚苯乙炔分子电子输运性质研究  

Electronic transport properties of oligo phenylene ethynylene molecule modified by the(CH_3)_2 and(NH_2)_2 groups

作　　者：辛建国[1] 杨传路[1] 王美山[1] 马晓光[1] 

机构地区：[1]鲁东大学物理与光电工程学院,烟台264025

出　　处：《物理学报》2016年第7期104-111,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11374132;11574125);山东省泰山学者计划(批准号:ts201511055)资助的课题~~

摘　　要：采用密度泛函理论和非平衡格林函数相结合的方法研究了S原子作为单、双端基的(CH_3)_2-OPE(齐聚苯乙炔)和(NH_2)_2-OPE分子在金电极间的电子输运性质.通过第一性原理优化计算获得分子部分稳定结构,再置于Au电极之间构成两极系统,然后再优化整个两极系统获得稳定结构.另外,通过非平衡格林函数方法计算了两极系统的电子输运性质.计算结果表明,不同的修饰基团和桥接方式可以导致两极系统的开关效应、负微分电阻行为和整流行为等不同的电子输运性质.通过计算不同偏压下的分子体系投影轨道电子分布、透射谱、态密度,对这些新异的电输运性质出现的机理进行了解释.The modification effects of the groups（CH_3）_2 and （NH_2）_2on the oligo phenylene ethynylene（OPE） molecules with single and double S atoms connected to the two electrodes are investigated by the density functional theory and non-equilibrium Green function. The modified OPE molecule is optimized and used to build a two-probe system with Au electrodes. Then the two-probe system is fully relaxed to obtain a stable structure. The electronic transport properties of the two-probe system are also calculated with the non-equilibrium Green function method. The calculation results show that both the modified groups and the bridge atoms can lead to the switch effect, the negative differential resistance behavior, and the rectifying behavior for the two-probe system. When molecules are connected with single S atom at one end, both the（NH_2）_2-OPE and the（CH_3）_2-OPE molecules show the rectifying behavior. However, the （NH_2）_2-OPE also shows a switch effect at larger voltage because there is current when the negative bias is over 1.3 V, while the（CH_3）_2-OPE molecule demonstrates a complete rectifying behavior because it is hardly conductive in the whole positive bias area. The current of OPE molecule without modification group always increases with the increase of voltage. Therefore, it is only a resistance. These results are different from that of NO2-OPE-NH2 molecule which shows a negative differential resistance behavior. For the case of the molecule connected with S atoms at both ends, the （NH_2）_2-OPE（S） and（CH_3）_2-OPE（S）models show negative differential resistance behaviors in the negative bias range. It is found that both （NH_2）_2-OPE and（CH_3）_2-OPE molecules demonstrate the negative differential resistance behaviors when they are connected with S atoms bridge at both ends. However, the current of the molecule with one S atom at one end is about two-order magnitude lower than that of the molecule with S atoms at both ends. It is shown that S atom acting as a bridg

关 键 词：开关效应 负微分电阻 整流 密度泛函理论 

分 类 号：O632.1[理学—高分子化学]