Charge Transport through Superexchange in Phenothiazine–7,7,8,8-Tetracyanoquinodimethane (PTZ–TCNQ) Cocrystal Microribbon FETs Grown Using Evaporative Alignment
Charge Transport through Superexchange in Phenothiazine–7,7,8,8-Tetracyanoquinodimethane (PTZ–TCNQ) Cocrystal Microribbon FETs Grown Using Evaporative Alignment
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DOI：
10.1021/acsaelm.2c01160
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发表时间：
2022-11
影响因子：
4.7
通讯作者：
S. Melis;Samantha T. Hung;C. Bagade;Y. Chung;Eleni Hughes;Xinran Zhang;P. Barbara;P. Han;Tingting Li;Daniel McCusker;Robert Hartsmith;Jeffery A. Bertke;P. Dev;Iris Stone;Jaydeep Joshi;P. Vora;E. Van Keuren
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作者：
S. Melis;Samantha T. Hung;C. Bagade;Y. Chung;Eleni Hughes;Xinran Zhang;P. Barbara;P. Han;Tingting Li;Daniel McCusker;Robert Hartsmith;Jeffery A. Bertke;P. Dev;Iris Stone;Jaydeep Joshi;P. Vora;E. Van Keuren
电荷转移 (CT) 共晶体是由电子给予和接受物质组成的分子晶体，正在开发用于光电子学应用。在这里，我们展示了 CT 共晶吩噻嗪-四氰基醌二甲烷 (PTZ-TCNQ) 的光学和电子表征。该材料具有宽的近红外吸收峰，光带边缘小于 0.6 eV。我们使用密度泛函理论计算来确定低能 CT 态的起源和拉曼光谱的变化。我们还演示了使用蒸发排列方法制造长的带状定向共晶。在硅衬底上生长的共晶被制造成有机场效应晶体管。尽管理论上预测了双极性，但仅观察到电子传导，迁移率约为 10–4cm2V–1s–1。迁移率温度依赖性的测量表明电荷传输存在超交换介导的跳跃机制，其特征能级为 0.19 eV。
Charge transfer (CT) cocrystals, molecular crystals composed of electron donating and accepting species, are being developed for applications in optoelectronics. Here we present optical and electronic characterization of the CT cocrystal phenothiazine–tetracyanoquinodimethane (PTZ–TCNQ). This material has a broad NIR absorption peak with an optical band edge less than 0.6 eV. We used density functional theory calculations to identify the origin of the low energy CT states and changes in the Raman spectra. We also demonstrate the fabrication of long, ribbon-like oriented cocrystals using an evaporative alignment method. Cocrystals grown on Si substrates were fabricated into organic field effect transistors. Despite theoretical predictions of ambipolarity, only electron conduction was observed, with mobilities on the order of 10–4cm2V–1s–1. Measurements of the temperature dependence of the mobility indicated a superexchange mediated hopping mechanism for charge transport, with a characteristic energy scale of 0.19 eV.