Giant Enhancement of Excitonic Electro-optic Response in Trap-Reduced Organic Transistors
Giant Enhancement of Excitonic Electro-optic Response in Trap-Reduced Organic Transistors
复制标题
陷阱减少有机晶体管中激子电光响应的巨大增强
DOI：
10.1103/physrevapplied.16.044043
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发表时间：
2021
影响因子：
4.6
通讯作者：
Hasegawa Tatsuo
中科院分区：
文献类型：
--
作者：
Matsuoka Satoshi;Tsutsumi Jun'ya;Hasegawa Tatsuo
当有机场效应晶体管（FET）涉及具有高度疏水性栅极电介质层的陷阱消除半导体界面时，它们表现出优异的开关特性。在这项研究中，我们调查激子电光响应离域载流子积累在陷阱消除界面的并五苯单晶场效应晶体管。我们发现，栅极调制（GM）成像，灵敏地可视化之间的栅极导通和栅极关断状态的光学显微镜图像的变化，独家揭示了独特的增强电光响应下的漏极电压的应用（）。无偏GM图像呈现出均匀的空间分布，这与沟道中的累积载流子密度一致。与此相反，偏置GM图像呈现出奇特的空间分布，在源极和漏极的边缘附近具有相当急剧的增加。此外，观察到以下有趣的特征：（1）GM信号分布在电极边缘附近的急剧增加与Kelvin探针力显微镜测量的横向电场分布相似，以及（2）从在不同波长下测量的相应GM图像中提取的GM光谱呈现出类似于二阶导数的形状，这意味着激子吸收的加宽。基于这些观察，我们调查的起源，这种独特的效果在增强违反激子相干离域载流子积累下漏偏置。与浅陷阱弱结合的栅诱导空穴应通过横向电场脱陷，这最终产生价带空穴，从而增强电光响应。这些发现应该阐明的空间相干的分子激子，负责各种独特的光电特性的有机电子器件。
Organic field-effect transistors (FETs) exhibit excellent switching characteristics when they involve trap-eliminated semiconductor interfaces with highly hydrophobic gate dielectric layers. In this study, we investigate the excitonic electro-optic response by delocalized carrier accumulation at the trap-eliminated interfaces of pentacene single-crystal FETs. We find that gate-modulation (GM) imaging, which sensitively visualizes the variation in optical microscope images between the gate-onand gate-offstates, exclusively reveals the unique enhancement of electro-optic response under the application of drain voltages (). The-unbiased GM image exhibits a uniform spatial distribution, which is consistent with the accumulated carrier density in the channel. In contrast, the-biased GM image presents a peculiar spatial distribution with fairly sharp increases around the edges of the source and drain electrodes. Furthermore, the following intriguing features are observed: (1) The sharp increase in the GM signal distribution around the electrode edge is similar to the lateral electric field distribution as measured by Kelvin probe force microscopy, and (2) the GM spectra, extracted from the respective GM images measured at different wavelengths, present a second-derivative-like shape that implies the broadening of exciton absorption. Based on these observations, we investigate the origin of this unique effect in terms of the enhanced violation of exciton coherence by delocalized carrier accumulations under drain bias. The gate-induced holes that are weakly bound to shallow traps should be detrapped by lateral electric fields, which eventually generate valence band holes and thus enhance the electro-optic response. These findings should elucidate the spatial coherence of the molecular excitons that are responsible for the various unique photoelectric characteristics of organic electronic devices.