应用密度泛函理论研究了四种二萘嵌苯二酰亚胺(PDI)(N,N′-二萘嵌苯-3,4,9,10-四羧酸二酰亚胺(1),N,N′-二(3-氯苯甲基)二萘嵌苯-3,4,9,10-四羧酸二酰亚胺(2),N,N′-二(3-氟苯甲基)二萘嵌苯-3,4,9,10-四羧酸二酰亚胺(3)和N,N′-二(3,3-二氟苯甲基)二萘嵌苯-3,4,9,10-四羧酸二酰亚胺(4))半导体材料的最高占据轨道和最低未占据轨道能量、离子化能和电子亲和能以及在电荷传导过程中的重组能.与化合物2-4的最高占据轨道和最低未占据轨道能量变化相同,在PDI分子外围引入氯苯甲基或氟苯甲基后导致化合物2-4的绝热电子亲和能有不同程度的增加.应用Marcus电子传导理论,计算了这四种半导体材料应用于有机场效应晶体管在电子传递过程中的电子耦合和迁移率.计算结果表明:这四种化合物相对于金属金电极而言具有较小的电子注入势垒,是优良的n型半导体材料.计算的这四种半导体材料的电子传输迁移率分别为5.39,0.59,0.023和0.17cm2·V-1·s-1.通过研究化合物分子在还原过程中几何结构变化和在化合物3晶体中不同类型的电子传递路径,合理地解释了化合物1-4在有机场效应晶体管电荷迁移过程中具有较高的电子迁移率.
Density functional theory (DFT) calculations were carried out to study the charge transfer properties of N,N'-bisperylene-3,4,9,10-tetracarboxylic diimide (1),N,N'-bis(3-chlorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (2),N,N'-bis(3-fluorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (3),and N,N'-bis(3,3-difluorobenzyl)perylene3,4,9,10-tetracarboxylic diimide (4) for use as organic field effect transistors (OFETs).The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies,ionization energy (IE),electron affinity (EA),and reorganization energy (λ) were investigated for these compounds.Corresponding to energy changes in the HOMO and LUMO for 2-4,the introduction of chlorobenzyl or fluorobenzyl groups leads to high adiabatic electron affinity (EAa) values for 2-4.The transfer integral (V) and field effect transistor (FET) properties for the four compounds with known crystal structures were calculated based on Marcus electron transfer theory.The calculated results reveal that a very small injection barrier exists relative to the Au source-drain electrode of 1-4 for electrons,producing good potential n-type semiconductors.Intrinsic electron transfer mobilities (μ-) of 5.39,0.59,0.023,and 0.17 cm2·V-1·s-1 were calculated for compounds 1-4,respectively.The high intrinsic electron mobilities for 1-4 were rationalized by examining the changes in geometric structure upon reduction and charge transfer integral for the different transfer modes in crystal 3.