van den Bersselaar Bart W L, van de Ven Alex P A, de Waal Bas F M, Meskers Stefan C J, Eisenreich F, Vantomme G
Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB, The Netherlands.
Polymer Performance Materials Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB, The Netherlands.
Adv Mater. 2024 Jun;36(23):e2312791. doi: 10.1002/adma.202312791. Epub 2024 Mar 7.
Spontaneous phase separation is a promising strategy for the development of novel electronic materials, as the resulting well-defined morphologies generally exhibit enhanced conductivity. Making these structures adaptive to external stimuli is challenging, yet crucial as multistate reconfigurable switching is essential for neuromorphic materials. Here, a modular and scalable approach is presented to obtain switchable phase-separated viologen-siloxane nanostructures with sub-5 nm features. The domain spacing, morphology, and conductivity of these materials can be tuned by ion exchange, repeated pulsed photoirradiation and electric stimulation. Counterion exchange triggers a postsynthetic modification in domain spacing of up to 10%. Additionally, in some cases, 2D to 1D order-order transitions are observed with the latter exhibiting a sevenfold decrease in conductivity with respect to their 2D lamellar counterparts. Moreover, the combination of the viologen core with tetraphenylborate counterions enables reversible and in situ reduction upon light irradiation. This light-driven reduction provides access to a continuum of conducting states, reminiscent of long-term potentiation. The repeated voltage sweeps improve the nanostructures alignment, leading to increased conductivity in a learning effect. Overall, these results highlight the adaptivity of phase-separated nanostructures for the next generation of organic electronics, with exciting applications in smart sensors and neuromorphic devices.
自发相分离是开发新型电子材料的一种很有前景的策略，因为由此产生的明确定义的形态通常具有增强的导电性。使这些结构适应外部刺激具有挑战性，但至关重要，因为多态可重构切换对于神经形态材料至关重要。在此，提出了一种模块化且可扩展的方法，以获得具有亚5纳米特征的可切换相分离紫精-硅氧烷纳米结构。这些材料的域间距、形态和导电性可以通过离子交换、重复脉冲光照射和电刺激来调节。抗衡离子交换会引发合成后域间距高达10%的修饰。此外，在某些情况下，会观察到从二维到一维的有序-有序转变，后者的导电性相对于其二维层状对应物降低了七倍。此外，紫精核心与四苯基硼酸抗衡离子的组合能够在光照下实现可逆的原位还原。这种光驱动还原提供了一系列导电状态，让人联想到长时程增强。重复的电压扫描改善了纳米结构的排列，在学习效应中导致导电性增加。总体而言，这些结果突出了相分离纳米结构对下一代有机电子学的适应性，在智能传感器和神经形态器件中有令人兴奋的应用。
