Fabrication and characterization of controllable grain boundary arrays in solution-processed small molecule organic semiconductor films
Fabrication and characterization of controllable grain boundary arrays in solution-processed small molecule organic semiconductor films
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DOI：
10.1063/1.3698203
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发表时间：
2012-04-01
影响因子：
3.2
通讯作者：
Anthony, John E.
中科院分区：
文献类型：
--
作者：
Wo, Songtao;Headrick, Randall L.;Anthony, John E.
我们已经生产了6，13-双（三异丙基甲硅烷基乙炔基）并五苯的溶液处理的薄膜，其晶粒尺寸从几微米到毫米级，通过从矩形触针横向结晶。晶粒沿着结晶方向取向，并且横向于结晶方向的晶粒尺寸与写入速度成反比，因此形成具有可控间距的取向晶界的规则阵列。我们利用这些可控阵列系统地研究了大角度晶界在薄膜晶体管中载流子输运和电荷捕获中的作用。有效的迁移率与晶粒尺寸成比例，导致在单个大角度晶界处的电位降估计超过1伏。该结果表明，晶界的结构不是分子突变的，这可能是溶液处理的小分子有机半导体薄膜的一般特征，其中通常形成相对高能量的晶界。从正到负的栅极偏置或大和小的负栅极偏置之间切换后的瞬态测量揭示可逆的电荷捕获，与时间常数的顺序为10秒和陷阱密度与晶界密度。我们认为电荷沿沿着晶界和其它缺陷的扩散是可逆俘获的速率决定机制。(C)2012年美国物理学会。[http：//dx.doi.org/10.1063/1.3698203]
We have produced solution-processed thin films of 6,13-bis(tri-isopropyl-silylethynyl) pentacene with grain sizes from a few micrometers up to millimeter scale by lateral crystallization from a rectangular stylus. Grains are oriented along the crystallization direction, and the grain size transverse to the crystallization direction depends inversely on the writing speed, hence forming a regular array of oriented grain boundaries with controllable spacing. We utilize these controllable arrays to systematically study the role of large-angle grain boundaries in carrier transport and charge trapping in thin film transistors. The effective mobility scales with the grain size, leading to an estimate of the potential drop at individual large-angle grain boundaries of more than 1 volt. This result indicates that the structure of grain boundaries is not molecularly abrupt, which may be a general feature of solution-processed small molecule organic semiconductor thin films, where relatively high energy grain boundaries are typically formed. Transient measurements after switching from positive to negative gate bias or between large and small negative gate bias reveal reversible charge trapping, with time constants on the order of 10 s and trap densities that are correlated with grain boundary density. We suggest that charge diffusion along grain boundaries and other defects is the rate-determining mechanism of the reversible trapping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3698203]