Liu Wei, Khorsand Ahmadi Mohammad, Dekkers Max H J, Henzen Alex, den Toonder Jaap M J, Yuan Dong, Groenewold Jan, Zhou Guofu, Wyss Hans M
Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China; Department of Mechanical Engineering, Microsystems, Eindhoven University of Technology, Eindhoven, 5600 MB, Netherlands; Institute for Complex Molecular Systems [ICMS], Eindhoven University of Technology, Eindhoven, 5600 MB, Netherlands.
Department of Mechanical Engineering, Microsystems, Eindhoven University of Technology, Eindhoven, 5600 MB, Netherlands; Institute for Complex Molecular Systems [ICMS], Eindhoven University of Technology, Eindhoven, 5600 MB, Netherlands.
J Colloid Interface Sci. 2025 Jan 15;678(Pt C):449-459. doi: 10.1016/j.jcis.2024.09.022. Epub 2024 Sep 11.
Nonpolar solvents with added charge control agents are widely used in various applications, such as E-paper displays. In spite of previous work, the mechanisms governing charge generation in nonpolar liquids, particularly those induced by electrochemical reactions at the liquid-solid interface, are not completely understood. We hypothesize that a physics-based model, according to the modified Butler-Volmer equation, can be used to quantitatively predict the injection of charges and the corresponding currents, in nonpolar solvents with surfactants.
We propose a model to describe the migration and charge generation of inverse micelles. In addition to the mechanisms of electromigration, diffusion and charge generation via disproportionation that were introduced in earlier models, we include charge generation via electron injection at the electrodes using a microscopically justified expression as opposed to the previously used semi-empirical approaches. To validate our model, we compare its results to experimental current measurements in a simplified, effectively 1D, geometry.
We find that the incorporation of both bulk and electrochemical reaction mechanisms in the model can effectively explain the experimental steady-state currents in a wide range of concentrations, voltages (0.5 V-5 V), and cell thicknesses. These numerical results of currents at longer time scales show a steady-state current only when both bulk and electrochemical reactions are taken into account. Moreover, we have observed in our simulation that at low applied voltages, the electric field in the bulk is fully shielded, and the steady-state current in this low-voltage regime is governed by the charge injection at the electrodes. Conversely, when the voltage is high enough and the electric field remains partially unscreened, the bulk disproportionation mechanism dominates the current generation. This also explains why we observe a non-Ohmic behavior where the steady-state currents at high voltages are independent of applied voltage. Hence, by elucidating the physical processes underlying the experimental observations, our model offers a more profound comprehension of charge transport in these systems, which could facilitate advancements in the design of enhanced E-ink displays and smart windows.
添加了电荷控制剂的非极性溶剂广泛应用于各种领域，如电子纸显示器。尽管此前已有相关研究，但非极性液体中电荷产生的机制，尤其是液 - 固界面处电化学反应所引发的电荷产生机制，尚未被完全理解。我们推测，基于物理的模型，依据修正的巴特勒 - 沃尔默方程，可用于定量预测在含有表面活性剂的非极性溶剂中电荷的注入及相应电流。
我们提出一个模型来描述反胶束的迁移和电荷产生。除了早期模型中引入的电迁移、扩散以及通过歧化反应产生电荷的机制外，我们采用微观合理的表达式，而非先前使用的半经验方法，纳入了通过电极处电子注入产生电荷的机制。为验证我们的模型，我们将其结果与在简化的、有效一维几何结构中的实验电流测量结果进行比较。
我们发现，在模型中纳入本体和电化学反应机制，能够有效解释在广泛的浓度、电压（0.5 V - 5 V）和电池厚度范围内的实验稳态电流。这些较长时间尺度下电流的数值结果表明，只有同时考虑本体和电化学反应时，才会出现稳态电流。此外，我们在模拟中观察到，在低施加电压下，本体中的电场被完全屏蔽，此低电压 regime 下的稳态电流由电极处的电荷注入控制。相反，当电压足够高且电场仍部分未被屏蔽时，本体歧化机制主导电流产生。这也解释了为何我们观察到非欧姆行为，即高电压下的稳态电流与施加电压无关。因此，通过阐明实验观测背后的物理过程，我们的模型为这些系统中的电荷传输提供了更深刻的理解，这有助于推动增强型电子墨水显示器和智能窗户设计的进步。
