Triggering WORM/SRAM memory conversion in a porphyrinated polyimide via Zn complexation as the internal electrode.
Khan Qudrat Ullah, Jia Nanfang, Tian Guofeng, Qi Shengli*, and Wu Dezhen
Journal of Physical Chemistry C, 2017, 121: 9153–9161.
【摘要】We design two novel solution processable polyimides (PIs), NH-Por-6FDA and Zn-Por-6FDA, with 5,15-bis(4,-aminophenyl)-10,20-diphenylporphyrin (trans-DATPP) (electron donor) and 4,4′-(hexafluoroisoprpoylidine)diphthalic anhydride (6FDA) (electron acceptor) as the building blocks for polymer memory applications. The chemical structures of the two polymers are mostly identical with the only difference lying in the zinc ion (Zn2+) insertion into the porphyrin core in the Zn-Por-6FDA. Electrical characterization indicates that the NH-Por-6FDA possesses bidirectional nonvolatile write once read many times (WORM) memory behavior, while the Zn-Por-6FDA shows vastly different volatile static random access memory (SRAM) behavior. Both polymer memory devices show high ON/OFF current ratio up to 106 and exhibit excellent long-term operation stability in 108 read cycles and retention time of 4000 s with no current degradation. The charge transfer (CT) and function of the donor/acceptor moiety in the polymers related with the electrical switching effect are elucidated on the basis of optical, electrochemical measurement, and quantum simulation results. The inserted zinc ion in the porphyrin is suggested to form an internal electrode and act as a bridge during the electronic transition process, which facilitates both the CT and back CT, consequently triggering the WORM/SRAM conversion upon Zn complexation. The results observed here indicate the significance of metal-complexation on the memory effects, and will attract the attention of the researchers to use noble transition metals for the suitable expecting memory devices.
