General observation of n-type field-effect behaviour in organic semiconductors
General observation of n-type field-effect behaviour in organic semiconductors
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DOI：
10.1038/nature03376
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发表时间：
2005-03-10
期刊：
影响因子：
64.8
通讯作者：
Friend, RH
中科院分区：
文献类型：
--
作者：
Chua, LL;Zaumseil, J;Friend, RH
十多年来，有机半导体一直是积极研究的主题，其应用出现在发光显示器和可印刷电子电路中。这些材料的一个特征是电子而不是空穴的强捕获（1）：有机场效应晶体管（FET）通常显示p型而不是n型导电，即使使用适当的低功函数电极，除了一些特殊的高电子亲和性（2-4）或低带隙（5）有机半导体。在这里，我们证明了使用适当的无羟基栅极电介质-如二乙烯基四甲基双（苯并环丁烯）衍生物（BCB;参考文献6）-可以在大多数共轭聚合物中产生n沟道FET导电。由此获得的FET电子迁移率揭示了电子在这些材料中比以前认为的更移动的。在一些聚芴共聚物和二烷基取代的聚（对苯撑乙烯）中测量了10（-3）到10（-2）cm（2）V-1 s（-1）量级的电子迁移率，所有这些都是在未取向状态下。我们进一步表明，为什么n型行为以前是如此难以捉摸的原因是在半导体-电介质界面处的电子被羟基捕获，在常用的SiO2电介质的情况下，羟基以硅烷醇的形式存在。因此，这些发现应该为有机互补金属氧化物半导体（CMOS）电路开辟新的机会，其中p型和n型行为都被利用。
Organic semiconductors have been the subject of active research for over a decade now, with applications emerging in light-emitting displays and printable electronic circuits. One characteristic feature of these materials is the strong trapping of electrons but not holes(1): organic field-effect transistors (FETs) typically show p-type, but not n-type, conduction even with the appropriate low-work- function electrodes, except for a few special high-electron-affinity(2-4) or low-bandgap(5) organic semiconductors. Here we demonstrate that the use of an appropriate hydroxyl-free gate dielectric - such as a divinyltetramethylsiloxanebis( benzocyclobutene) derivative ( BCB; ref. 6) - can yield n-channel FET conduction in most conjugated polymers. The FET electron mobilities thus obtained reveal that electrons are considerably more mobile in these materials than previously thought. Electron mobilities of the order of 10(-3) to 10(-2) cm(2) V-1 s(-1) have been measured in a number of polyfluorene copolymers and in a dialkyl-substituted poly(p-phenylenevinylene), all in the unaligned state. We further show that the reason why n-type behaviour has previously been so elusive is the trapping of electrons at the semiconductor - dielectric interface by hydroxyl groups, present in the form of silanols in the case of the commonly used SiO2 dielectric. These findings should therefore open up new opportunities for organic complementary metal-oxide semiconductor (CMOS) circuits, in which both p-type and n-type behaviours are harnessed.