Interlayer Resistance and Edge-Specific Charging in Layered Molecular Crystals Revealed by Kelvin-Probe Force Microscopy
Interlayer Resistance and Edge-Specific Charging in Layered Molecular Crystals Revealed by Kelvin-Probe Force Microscopy
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DOI：
10.1021/acs.jpcc.5b00611
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
Y. Yamagishi;K. Noda;K. Kobayashi;Hirofumi Yamada
中科院分区：
文献类型：
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作者：
Y. Yamagishi;K. Noda;K. Kobayashi;Hirofumi Yamada
用开尔文探针力显微镜（KFM）研究了具有溶液处理的2，7-二辛基[1]苯并噻吩并[3，2-B][1]苯并噻吩（C8-BTBT）有源沟道的有机场效应晶体管（OFFET）。我们发现在沟道区中的阶梯状电位分布，这表明共轭BTBT核心层之间的层间电阻是相当高的，并且每个共轭层通过绝缘烷基链层彼此电隔离。我们还发现了一个明显的正电荷在沟道区，特别是在设备操作后的步骤边缘。观察到的充电解释由长寿命的正电荷的陷阱网站上，和陷阱密度在台阶边缘估计为1011 cm-2的顺序。KFM测量表明，交错的C8-BTBT OFFET的器件性能可能会恶化，由于相当高的访问电阻，这源于高的层间电阻和/或通过特定的位置电荷捕获在半导体层的。
Organic field-effect transistors (OFETs) having an active channel of solution-processed 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8–BTBT) were investigated by Kelvin-probe force microscopy (KFM). We found step-like potential distributions in a channel region, suggesting that the interlayer resistance between the conjugated BTBT core layers is quite high and each conjugated layer is electrically isolated from one another by insulating alkyl chain layers. We also found a noticeable positive charging in the channel region especially at the step edges after the device operation. The observed charging was explained by long-lived positive charges on the trap sites, and the trap density at the step edge was estimated to be on the order of 1011 cm–2. The KFM measurements suggest that the device performance of the staggered C8–BTBT OFETs could deteriorate due to the considerably high access resistance, which stems from the high interlayer resistance and/or by the site-specific charge trapping at the cont...