摘要
近年来,有机半导体在在发光二极管、场效应晶体管和太阳能电池等方面的得到越来越多的应用。载流子迁移率的性质作为衡量有机半导体性能好坏的重要指标之一,在实验和理论计算方面都发展了大量的研究方法。我们结合量化计算和马库斯电荷转移理论,分析四种硫代NDI分子晶体结构中电子和空穴传输的各向异性特性。我们的计算结果和实验数据可以较好地吻合,但是由于实验中测量的是薄膜中载流子迁移率的性质,与我们计算的单晶结构会有一定的误差。四种单晶的迁移率均表现出较强的各向异性,并且随着硫原子数的增加电子和空穴的迁移率均有较大程度的增大。其中互为顺反异构体的trans-S2和cis-S2均表现出n型半导体的性质,并且反式结构的电子和空穴的迁移率均大于顺式结构,这与其他文献中顺反异构体迁移率的性质是一致的。另外,我们的计算结果发现,载流子迁移率最大的方向不一定是分子最近的堆积方向,而是在电荷耦合最强的方向,这为下一步有机半导体的设计和改进提供有力的帮助和指导。
Organic semiconductors(OSC) have gained much applications in LED, FETs and solar cells. The propriety of carrier mobility is one of the most important parameter for assessing OSC. Based on quantum-chemical calculations and Marcus theory, the carrier mobility properties of four thionated naphthalene diimides crystal were calculated in detail. The four crystals all show largely anistropic mobilities, while the hole-and electron-mobilities increased with the number of sulfur atom. The trans-S2 has a larger carrier mobility of hole and electron than cis-S2, which are consistent with the research on cis-trans-isomer. These results provides a guide for the optimization OSC performance by analyzing the relationship between propriety of carrier mobility and molecular crystal structures.
引文
[1]Wen,S.H.;Li,A.;Song,J.L.;Deng,W.Q.;Han,K.L.;Goddard,W.A.,J Phys Chem B 2009,113,8813-8819.
[2]Kozycz,L.M.;Guo,C.;Manion,J.G.;Tilley,A.J.;Lough,A.J.;Li,Y.N.;Seferos,D.S.,Journal of Materials Chemistry C 2015,3,11505-11515.
[3]Deng,W.Q.;Sun,L.;Huang,J.D.;Chai,S.;Wen,S.H.;Han,K.L.,Nat Protoc 2015,10,632-642.