Observation of ambipolar field-effect behavior in donor–acceptor conjugated copolymers

ABSTRACTThe effects of substitute side chain were investigated using donor-acceptor (D-A) conjugated copolymers consisting of a cyclopentadithiophene (CPDT) derivative and dithienyl-benzothiadiazole (DTBT). The intrinsic properties of the copolymers were significantly altered by perturbations of the intramolecular charge transfer (ICT). The absorption of PCPDT-ttOTBTOT (P2), which assumed a tail-tail configuration, tended to blue-shift relative to the absorption of PCPDT-TBTT (P1). The absorption of PCPDT-hhOTBTOT (P3), which assumed a head-head configuration, was blue-shifted relative to that of P2. The electrical transport properties of field-effect transistors (FETs) were sensitive to the side chain position. The field-effect mobility in P2 (μ2=1.8×10–3 cm2/V·s) was slightly lower that in P1 (μ1=4.9×10–3 cm2/V·s). The mobility of P3, however, was very low (μ3=3.8×10–6 cm2/V·s). Photoexcitation spectroscopy showed that the charge generation efficiency (shown in transient absorption spectra) and polaron pair mobility in P1 and P2 were higher than in P3, yielding P1 and P2 device performances that were better than the performance of devices based on P3.

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Hysteresis Behavior of the Donor–Acceptor-Type Ambipolar Semiconductor for Non-Volatile Memory Applications

Micromachines ◽

10.3390/mi12030301 ◽

2021 ◽

Vol 12 (3) ◽

pp. 301

Author(s):

Young Jin Choi ◽

Jihyun Kim ◽

Min Je Kim ◽

Hwa Sook Ryu ◽

Han Young Woo ◽

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Keyword(s):

Organic Semiconductor ◽

Field Effect ◽

Field Effect Transistor ◽

Memory Device ◽

Non Volatile Memory ◽

Device Applications ◽

Donor Acceptor ◽

Effect Transistor ◽

Volatile Memory ◽

Memory Applications

Donor–acceptor-type organic semiconductor molecules are of great interest for potential organic field-effect transistor applications with ambipolar characteristics and non-volatile memory applications. Here, we synthesized an organic semiconductor, PDPPT-TT, and directly utilized it in both field-effect transistor and non-volatile memory applications. As-synthesized PDPPT-TT was simply spin-coated on a substrate for the device fabrications. The PDPPT-TT based field-effect transistor showed ambipolar electrical transfer characteristics. Furthermore, a gold nanoparticle-embedded dielectric layer was used as a charge trapping layer for the non-volatile memory device applications. The non-volatile memory device showed clear memory window formation as applied gate voltage increases, and electrical stability was evaluated by performing retention and cycling tests. In summary, we demonstrate that a donor–acceptor-type organic semiconductor molecule shows great potential for ambipolar field-effect transistors and non-volatile memory device applications as an important class of materials.

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Oligofuran–Benzothiadiazole Co-oligomers: Synthesis, Optoelectronic Properties and Reactivity

Organic Materials ◽

10.1055/s-0041-1729853 ◽

2021 ◽

Vol 03 (02) ◽

pp. 303-308

Author(s):

Dror Ben Abba Amiel ◽

Choongik Kim ◽

Ori Gidron

Keyword(s):

Organic Solar Cells ◽

Field Effect ◽

Field Effect Transistors ◽

Organic Light Emitting Diodes ◽

Organic Field Effect Transistors ◽

Active Materials ◽

Light Emitting ◽

Organic Light ◽

Donor Acceptor ◽

Optical Bandgaps

Donor–acceptor–donor (DAD) triad systems are commonly applied as active materials in ambipolar organic field-effect transistors, organic solar cells, and NIR-emitting organic light-emitting diodes. Often, these triads utilize oligothiophenes as donors, whereas their oxygen-containing analogs, oligofurans, are far less studied in this setup. Here we introduce a family of DAD triads in which the donors are oligofurans and the acceptor is benzothiadiazole. In a combined computational and experimental study, we show that these triads display optical bandgaps similar to those of their thiophene analogs, and that a bifuran donor is sufficient to produce emission in the NIR spectral region. The presence of a central acceptor unit increases the photostability of oligofuran-based DAD systems compared with parent oligofurans of the similar length.

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