Effects of the acceptor conjugation length and composition on the electrical memory characteristics of random copolyimides
Effects of the acceptor conjugation length and composition on the electrical memory characteristics of random copolyimides
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DOI：
10.1002/pola.26502
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发表时间：
2013-03
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通讯作者：
Tadanori Kurosawa;Yi-Cang Lai;An-dih Yu;Hung‐Chin Wu;Tomoya Higashihara;M. Ueda;Wen‐Chang Chen
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作者：
Tadanori Kurosawa;Yi-Cang Lai;An-dih Yu;Hung‐Chin Wu;Tomoya Higashihara;M. Ueda;Wen‐Chang Chen
以4，4 ′-二氨基-4 ″-甲基三苯胺（AMTPA）、4，4 ′-（六氟异亚丙基）二邻苯二甲酸酐（DAPA）、N，N′-双（4-氨基苯基）-1，8：4，5-萘四甲酸二酰亚胺（NTCDI）或N，N ′-双（4-氨基苯基）-1，2：4，5-苯四甲酸二酰亚胺（BTCDI）为原料，制备了基于共聚聚酰亚胺（coPI）、PI-NTCDIX和PI-BTCDIX的阻变存储器。通过改变单体的投料比，PI-NTCDIX和PI-BTCDIX通过AMTPA与NTCDI或BTCDI之间的电荷转移（CT）表现出可调的光学和电学性质。随着NTCDI组分的增加，基于PI-NTCDIX的存储器件表现出从易失性动态随机存取存储器到非易失性一次写入多次读取存储器的可调电双稳态特性。通过对模型化合物的分析和密度泛函理论的计算，认为开关转变主要是电荷分离高电导的CT机制所致。此外，存储器件的挥发性取决于CT复合物的稳定性。NTCDI部分的长共轭和高电子亲和力稳定了CT复合物中产生的自由基阴离子，并防止了分离的自由基物种的重组，即使通过施加高的正或负电压。另一方面，与基于PI-NTCDIX的存储器件相比，基于PI-BTCDIX的存储器件表现出相当独特的行为。在低BTCDI组成下，器件表现出易失性存储特性。然而，由于BTCDI的最高占据分子轨道能级低，在高BTCDI组合物下没有观察到切换行为。结合这些结果和我们以前对perylenebisimide（PBI）的研究，我们得出结论，可以通过改变随机coPI中的共轭长度（PBI > NTCDI > BTCDI）和受体组成来定制记忆特性。© 2012 Wiley Periodicals，Inc. J Polym Sci Part A：Polym Chem，2013
Resistive-switching memories based on copolyimides (coPIs), PI-NTCDIX and PI-BTCDIX, with different compositions of 4,4′-diamino-4″-methyltriphenylamine (AMTPA), 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, and N,N′-bis-(4-aminophenyl)-1,8:4,5-naphthalenetetracarboxydiimide (NTCDI) or N,N′-bis-(4-aminophenyl)-1,2:4,5-benzenetetracarboxydiimide (BTCDI) have been developed. By varying the feed ratio of monomers, PI-NTCDIX and PI-BTCDIX showed tunable optical and electronic properties through the charge transfer (CT) between AMTPA and NTCDI or BTCDI. The memory devices based on PI-NTCDIX exhibited the tunable electrical bistability from the volatile dynamic random access memory to nonvolatile write once read many memory characteristics as the NTCDI composition increased. The OFF/ON electrical switching transition was mainly attributed to the CT mechanism for the charge separated high conductance, based on the analysis of model compounds and density functional theory calculation. Also, the volatility of the memory device depended on the stability of CT complex. The long conjugation and high electron affinity of the NTCDI moiety stabilized the radical anion generated in the CT complex and prevented the recombination of segregated radical species even through applying the high positive or negative voltage. On the other hand, the memory devices based on PI-BTCDIX showed a rather unique behavior compared with those based on PI-NTCDIX. At the low BTCDI composition, the device exhibited volatile memory property. However, no switching behavior was observed at the high BTCDI composition due to the low highest occupied molecular orbital energy level of BTCDI. Combining these results and our previous study on perylenebisimide (PBI), we concluded that memory characteristics could be tailored by changing the conjugation length (PBI > NTCDI > BTCDI) and the acceptor composition in random coPIs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013