Liang Yuanying, Tang Haoran, Zhang Chunyang, Liu Chunchen, Lan Linfeng, Huang Fei
Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou510640, China.
ACS Appl Mater Interfaces. 2022 Nov 16;14(45):51165-51174. doi: 10.1021/acsami.2c15934. Epub 2022 Nov 6.
The state-of-the-art poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-based organic electrochemical transistors (OECTs) are gaining importance for a variety of biological applications due to their mixed electronic and ionic conductivities featuring ion-to-electron conversion. A low operation voltage without sacrificing device performance is desired to realize long-term monitoring of biological activities. In the present work, oxoammonium salts with two different counterions (TEMPOX, where TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxoammonium; X = Br and TFSI) are employed as secondary dopants to modulate the device performance. Both oxoammonium salts feature a distinct dopant concentration-dependent doping effect, allowing precise control in improving the performance of OECTs. A zero-gate bias, corresponding to the maximum transconductance, and a low threshold voltage are realized by optimizing the dopant concentrations. In addition, TEMPOTFSI dopant exerts great capability in modulating the work function and in morphology reconstruction of PEDOT:PSS, ensuring a well-matched work function at the gold electrode-channel material interface and condensed microstructure stacking with an edge-on orientation in the doped PEDOT:PSS films. The synergistic effect of TEMPO and the TFSI counterion endows the device with superior performance to its counterparts due to the resultant higher μ* figure, benefiting from the efficient injection/extraction of holes at the interface and enhanced intra- and inter-chain carrier transport. The excellent device performance makes the OECT a promising neuromorphic device to mimic basic brain functions.
基于聚（3,4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT:PSS）的先进有机电化学晶体管（OECTs）因其具有离子到电子转换的混合电子和离子导电性，在各种生物应用中变得越来越重要。为了实现对生物活动的长期监测，需要在不牺牲器件性能的情况下实现低工作电压。在本工作中，使用具有两种不同抗衡离子的氧鎓盐（TEMPOX，其中TEMPO = 2,2,6,6-四甲基哌啶-1-氧鎓；X = Br和TFSI）作为二次掺杂剂来调节器件性能。两种氧鎓盐都具有明显的掺杂剂浓度依赖性掺杂效应，能够在提高OECTs性能方面进行精确控制。通过优化掺杂剂浓度，实现了对应于最大跨导的零栅极偏置和低阈值电压。此外，TEMPOTFSI掺杂剂在调节功函数和PEDOT:PSS的形貌重构方面具有很大能力，确保在金电极-沟道材料界面处功函数良好匹配，并且在掺杂的PEDOT:PSS薄膜中形成边缘取向的凝聚微观结构堆叠。由于在界面处空穴的有效注入/提取以及链内和链间载流子传输的增强，TEMPO和TFSI抗衡离子的协同效应赋予器件优于同类器件的性能，这得益于更高的μ*值。优异的器件性能使OECT成为一种有前途的神经形态器件，可用于模拟基本的脑功能。
