Stretchable OFET Memories: Tuning the Morphology and the Charge-Trapping Ability of Conjugated Block Copolymers through Soft Segment Branching
Stretchable OFET Memories: Tuning the Morphology and the Charge-Trapping Ability of Conjugated Block Copolymers through Soft Segment Branching
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DOI：
10.1021/acsami.0c18820
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发表时间：
2021-01-11
影响因子：
9.5
通讯作者：
Chen, Wen-Chang
中科院分区：
文献类型：
--
作者：
Hsu, Li-Che;Isono, Takuya;Chen, Wen-Chang
电荷捕获聚合物驻极体的力学性能和结构设计的灵活性使其在有机场效应晶体管（OFET）存储器中得到广泛应用。例如，在聚芴基共轭/绝缘嵌段共聚物（bcp）的驻极体中，绝缘聚合物基体中的受限纤维状聚芴纳米结构充当了有效的空穴捕获位点，通过bcp的设计实现了可控的记忆性能。然而，很少有研究报道内在可拉伸电荷捕获材料及其存储器件的应用，并且尚未开发出一种实用的方法来将BCP驻极体的薄膜形态与其电荷捕获能力联系起来。在这项研究中，报道了一系列新的共轭/绝缘bcp，聚（9,9-二-正己基-2,7-芴）-嵌段聚（δ -癸内酯）s （PF-b-PDLx, x = 1-3）作为可拉伸的空孔捕获材料。利用具有相当分子量的线性和支链PDL嵌段，研究了聚合物结构对形貌和器件性能的影响。此外，从原子力显微镜图像中提取了聚芴纳米纤维在BCP膜上的覆盖面积，该覆盖面积与聚合物驻极体的捕获密度相关。支化的PDL片段不仅提高了bcp的拉伸性，而且调整了bcp的结晶度和相分离度，从而提高了它们的电荷捕获能力。以PF-b-PDL3为驻极体层的OFET存储器件显示出最大的存储窗口（102 V），并且可以在高达100%应变的情况下保持其性能。这项研究强调了BCP设计对于开发可拉伸电荷捕获材料的重要性。
The mechanical properties and structural design flexibility of charge-trapping polymer electrets have led to their widespread use in organic field-effect transistor (OFET) memories. For example, in the electrets of polyfluorene-based conjugated/insulating block copolymers (BCPs), the confined fiberlike polyfluorene nanostructures in the insulating polymer matrix act as effective hole-trapping sites, leading to controllable memory performance through the design of BCPs. However, few studies have reported intrinsically stretchable charge-trapping materials and their memory device applications, and a practical method to correlate the thin-film morphology of BCP electrets with their charge-trapping ability has not yet been developed. In this study, a series of new conjugated/insulating BCPs, poly(9,9-di-n-hexyl-2,7-fluorene)-block-poly(delta-decanolactone)s (PF-b-PDLx, x = 1-3), as stretchable hole-trapping materials are reported. The linear and branched PDL blocks with comparable molecular weights were used to investigate the effect of polymer architecture on morphology and device performance. Moreover, the coverage area of the polyfluorene nanofibers on the BCP films was extracted from atomic force microscopy images, which can be correlated with the trapping density of the polymer electrets. The branched PDL segments not only improve stretchability but also tailor crystallinity and phase separation of the BCPs, thus increasing their charge-trapping ability. The OFET memory device with PF-b-PDL3 as the electret layer exhibited the largest memory window (102 V) and could retain its performance at up to 100% strain. This research highlights the importance of the BCP design for developing stretchable charge-trapping materials.