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Organic Semiconductor Memory using Electronic Function of Photochromic Molecules

利用光致变色分子电子功能的有机半导体存储器

基本信息

批准号：
15350111
负责人：
TSUJIOKA Tsuyoshi
金额：
$ 7.68万
依托单位：
Osaka Kyoiku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Photochromic diarylethenes are well known materials which have thermal stability for both isomerization state and a fatigue resistance. In this study a novel principle of organic memory device using a photochromic molecule was studied. Such a memory device is based on a reversible isomerization reaction of a photochromic bistable molecule by an electric carrier injection. This is achieved by a carrier (hole and electron) encounter excitation of the molecule of a diarylethene derivative. The electron on lowest unoccupied molecular orbital level and the hole on highest occupied molecular orbital level of the molecule produce the excited state identical to that produced by photo excitation, so the molecule is transformed into another isomerization form. For the case of diarylethene derivatives, the ionization potential Ip of the molecule is changed according to its isomerization form. The closed-ring form (colored form) has Ip of 5.7 eV and the open-ring form (uncolored form) has above 6.2eV. The information readout is achieved by detecting the electric current through the molecule affected by the difference of Ip.A new nonsymmetrical bipolar diarylethene with a triphenylamine group and an oxadiazole group, which exhibited electron donor and acceptor characteristics, respectively, were designed. The thin film sample was used in the experiment to confirm the "writing" and "reading" principles. The memory device was consisted of an anode, a hole injection layer, a hole transport layer, a photochromic layer and cathode. Reversible electric current decrease was observed and, therefore, the isomerization reaction by carrier injection was successfully demonstrated.For the memory devices with an electron transport layer the information writing speed was considerably improved. This was attributed the effective electron injection and transport from the cathode. Development of the bipolar diarylethene derivative is required to achieve higher speed memory devices.

光致变色二芳基乙烯是公知的材料，其具有异构化状态的热稳定性和抗疲劳性。本研究探讨了一种利用光致变色分子制作有机存储器件的新原理。这种存储器件是基于通过电载流子注入的光致变色染料分子的可逆异构化反应。这是通过二芳基乙烯衍生物分子的载流子（空穴和电子）遭遇激发来实现的。分子的最低未占轨道能级上的电子和最高已占轨道能级上的空穴产生与光激发相同的激发态，从而使分子转化为另一种异构化形式。对于二芳基乙烯衍生物的情况下，分子的电离电位IP根据其异构化形式而改变。闭环形式（有色形式）的Ip为5.7 eV，开环形式（无色形式）的Ip高于6.2 eV。设计了一种新的非对称双极性二芳基乙烯，该双极性二芳基乙烯含有三苯胺基和恶二唑基，分别具有电子给体和电子受体特性.在实验中使用薄膜样品来确认“写”和“阅读”原理。该存储器件由阳极、空穴注入层、空穴传输层、光致变色层和阴极组成。实验结果表明，电子传输层的引入可以有效地提高存储器件的信息写入速度。这归因于阴极的有效电子注入和输运。需要开发双极性二芳基乙烯衍生物以实现更高速度的存储器件。