Donor-acceptor containing polymers have shown great potential for digital memory devices applications. However, the relations between effect of donor-acceptor in the molecular structure and their memory properties have not been fully investigated systematic. Therefore, the primary goal of this thesis is to design and synthesize series of high performance aromatic polymers containing different donor and acceptor moiety or different linkage group between donor and acceptor for discussing the donor-acceptor and linkage group effect to the memory property.
In the first part, we would to explore two distinct approaches, as shown in Figure 1.10, to fabricate the memory devices by blending the PCBM as the acceptor with the donor-containing P-TPA, or incorporating the electron acceptor anthrquinone covalently resulting P-TPAAQ and P-TPAOAQ, respectively. The goal of this part of research is developing the tunable memory characteristics due by the structural design of the electrical functionality and linkage group effect of the TPA-based polymer and morphological control over the embedded PCBM.
The TPA-containing with dual electron acceptor polyimides AQ-PIs and OAQ-PIs as shown in Figure 1.11, were used to fabricate the memory devices. In addition to the carbonyl or phthalimide acceptor moiety in main chain, the anthraquinone as pendent acceptor group was also introduced to TPA via ether linkage or directly attached into the backbone. The electron charge withdrawing capability of these two acceptors could be studied by molecular simulation, electrochemical, and spectroelectrochemical behaviors. Linkage effect and the electron-withdrawing effect would be investigated in second part of this thesis.
In the final topic of this thesis, three series of polymers with same TPA donor but containing different acceptor or different linkage group between donor and acceptor
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unit, as shown in Figure 1.12, will be prepared for high-performance polymeric memory devices and the following measurements. Then, the effect of different electro-withdrawing ability or different chain conformation caused distinct linkage group to their memory properties would be investigated systematically.
I-V
Al
ITO glass P-TPA:PCBM hybrid films
P-TPAAQ P-TPAOAQ PCBM P-TPA
Figure 1.10. Memory devices based on poly(triphenylamine)s derivatives and its PCBM hybrid film.
Al
I-V
Figure 1.11. Memory devices fabricated by functional polyimide containing TPA with dual competitive electron acceptors.
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Al I-V
ITO glass 50 nm polymer thin film PIs
PEs
PAs
High Performance Polymers With Different D-L-AContaining
for Memory Application
Figure 1.12. The approaching way for discussing the linkage group effect on their memory characteristic in corresponding D-L-A containing polymers of PIs, PAs, and PEs, and the schematic diagram of the memory device consisting of a polymer thin film sandwiched between an ITO bottom electrode and an Al top electrode.
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CHAPTER 2
Electrically Bistable Memory devices Derived from Poly(triphenylamine)s Derivatives and
its PCBM Hybrid Films
I-V
Al
ITO glass P-TPA:PCBM hybrid films
P-TPAAQ P-TPAOAQ PCBM P-TPA
37
ABSTRACT OF CHAPTER 2
In this chapter, we explore the tunable memory characteristics due to the structural design of the electrical functionality and linkage group effect of the TPA-based polymer synthesized via oxidative coupling reaction or morphological control over the embedded PCBM. P-TPA:PCBM hybrid films exhibited dynamic random access memory (DRAM) and write-once-read-many times (WORM) behavior in the sandwich configuration of ITO/ P-TPA:PCBM /Al controlled by the concentration of PCBM. The switching behavior could be associated with the charge transfer effect between TPA and PCBM. The devices with the sandwich structure of ITO/P-TPAAQ and P-TPAOAQ/Al exhibited the volatile bistable electrical switching characteristics of DRAM and SRAM, respectively. The charge transfer effect between the TPA donor moiety and incorporated pendent anthraquinone acceptor moiety and the introduced isolated ether group stabilized the charge transfer complex then extend the retention time could explain the switching phenomenon.
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