有机铁电材料的理论研究——从分子晶体设计到表面极化开关
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- 英文论文题名：Theoretical Study on Organic Ferroelectrics from Molecular Crystals to Two-Dimensional Self-Assembled Monolayers
- 论文作者：陈爽
- 英文论文作者：Shuang Chen ; Kuang Yaming Honors School ; Nanjing University
- 年：2016
- 作者机构：南京大学匡亚明学院;
- 论文关键词：理论模拟 ; 有机铁电体 ; 极化开关 ; 分子晶体 ; 表面自组装
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十分会：纳米体系理论与模拟
- 语种：中文
- 分类号：TB303
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十分会 ; 纳米体系理论与模拟
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：141k
- 原文格式：D
- 会议级别：全国
摘要
我们关于有机铁电材料的理论研究为设计室温铁电的分子晶体[1]和理解金属表面的自组装单层膜(甚至在电场下)的极性开关过程[2]提供了有价值的新认识。首先,我们设计了三种氢键组装的电荷转移复合物,它们均显示了很高的自发极化[1]。我们还发展了多尺度的模拟方法——结合Polymorph模块的蒙特卡洛退火和密度泛函框架下的几何结构优化来成功预测稳定的晶体结构[1]。然后在室温下Ag(111)面上的巴豆酸和Au(111)面上的玫瑰红酸二维单层膜的理论研究中,我们发现结构的热涨落能引起有机铁电单层膜二维平面内极化值的极大改变,甚至热涨落的贡献大到足以掩盖来自巴豆酸单层膜内自发的或者电场诱导的氢转移对极化值的贡献[2]。不同于巴豆酸,玫瑰红酸单层膜内没有自发的氢转移,甚至施加电场也不会引起膜内的氢转移[2]。无论巴豆酸还是玫瑰红酸单层膜在垂直表面的方向上有几乎不随热涨落和电场变化的极化值[2]。
Our theoretical study on organic ferroelectrics provides valuable insights to design molecular crystals with room-temperature ferroelectricity~1 and to understand polarization switching of self-assembled monolayers on metal surfaces even under an applied electric field.~2 First, three hydrogen-bonded charge transfer complexes were designed to exhibit high spontaneous polarizations.~1 To predict their energetically favorable packing structures, a computational approach that combines Polymorph predictor with density functional theory(DFT) geometry optimization was developed.~1 Secondly for two-dimensional sheets of croconic acid(CA) on Ag(111) surface and rhodizonic acid(RA) molecules on Au(111) surface at room temperature, thermal structural fluctuations of these hydrogen-bonded monolayers induced considerable polarization change within the film plane, which even could mask additional contributions to the polarization from spontaneous or electric field induced proton transfer in CA monolayer.~2 There was no proton transfer in RA monolayer.~2 Both CA and RA monolayers had constant polarization normal to the film plane.~2
Our theoretical study on organic ferroelectrics provides valuable insights to design molecular crystals with room-temperature ferroelectricity~1 and to understand polarization switching of self-assembled monolayers on metal surfaces even under an applied electric field.~2 First, three hydrogen-bonded charge transfer complexes were designed to exhibit high spontaneous polarizations.~1 To predict their energetically favorable packing structures, a computational approach that combines Polymorph predictor with density functional theory(DFT) geometry optimization was developed.~1 Secondly for two-dimensional sheets of croconic acid(CA) on Ag(111) surface and rhodizonic acid(RA) molecules on Au(111) surface at room temperature, thermal structural fluctuations of these hydrogen-bonded monolayers induced considerable polarization change within the film plane, which even could mask additional contributions to the polarization from spontaneous or electric field induced proton transfer in CA monolayer.~2 There was no proton transfer in RA monolayer.~2 Both CA and RA monolayers had constant polarization normal to the film plane.~2
引文
[1]Chen,S.;Zeng,X.C.J.Am.Chem.Soc.2014,136(17):6428.
[2]Chen,S.;Enders,A.;Zeng,X.C.Chem.Mater.2015,27(13):4839.
[2]Chen,S.;Enders,A.;Zeng,X.C.Chem.Mater.2015,27(13):4839.