Optical Measurements Revealing Nonuniform Hole Mobility in Organic Electrochemical Transistors
Optical Measurements Revealing Nonuniform Hole Mobility in Organic Electrochemical Transistors
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DOI：
10.1002/aelm.201500189
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发表时间：
2015-11-01
影响因子：
6.2
通讯作者：
McLeod, Robert R.
中科院分区：
文献类型：
--
作者：
Friedlein, Jacob T.;Shaheen, Sean E.;McLeod, Robert R.
理论预测和实验结果表明，共轭聚合物中的载流子迁移率取决于载流子浓度。然而，现有的有机电化学晶体管（OECT）模型假设载流子迁移率沿晶体管沟道一致，尽管载流子浓度存在变化。在这里，开发了一个包含无序引起的不均匀迁移率的模型来描述 OECT 的稳态行为。该模型使用 OECT 通道的原位光学测量进行测试，以解耦迁移率和载流子浓度对通道电导率的影响。研究发现，与现有模型不同，非均匀迁移率模型与这些测量结果一致。此外，我们发现该模型与各种器件几何形状和两种不同器件架构上的电流-电压数据相匹配。最后，结果表明，通过根据非均匀迁移率模型给出的器件参数（而不是从假设均匀迁移率的现有模型中提取的参数）操作传感器，可以获得 120% 的跨导改进。最终，所提出的模型允许通过晶体管表征更准确地测量材料特性。这将使材料优化更加明智，为 OECT 开发更准确的瞬态模型，并更有效地利用由现有材料制成的 OECT。
Theoretical predictions and experimental results show that the carrier mobility in conjugated polymers depends on carrier concentration. However, existing models for organic electrochemical transistors (OECTs) assume uniform carrier mobility along the transistor channel despite variations in carrier concentration. Here, a model incorporating disorder-induced nonuniform mobility is developed to describe the steady-state behavior of OECTs. This model is tested using in situ optical measurements of an OECT channel to decouple the mobility and carrier concentration contributions to channel conductivity. It is found that unlike existing models, the nonuniform mobility model agrees with these measurements. Furthermore, it is found that the model matches current-voltage data over a wide range of device geo metries and two different device architectures. Finally, it is shown that a 120% improvement of transconductance can be obtained by operating a sensor according to device parameters given by the nonuniform mobility model rather than those extracted from an existing model that assumes a uniform mobility. Ultimately, the model presented allows more accurate measurement of material properties via transistor characterization. This will enable better-informed material optimization, development of more accurate transient models for OECTs, and more effective use of OECTs made from existing materials.