ABSTRACT
In this paper we report three thiazole-flanked diketopyrrolopyrrole-based donor-acceptor alternating copolymers as new ambipolar semiconductors and their field-effect transistor devices with balanced hole and electron mobilities. Nitrile groups are introduced into the polymer backbone, and the substituent effect on electronic structures is studied. Different side chains are also involved to tune the interdigitation of the polymers. To probe the structural effects that contribute to the device performances, we provide insight into the thin-film microstructures and morphologies. Top-gate bottom-contact transistors fabricated under ambient conditions exhibit the impressive balanced hole and electron mobilities as high as 1.46 and 1.14 cm2 V-1 s-1, respectively, which are among the highest values reported for ambipolar thiazole-flanked diketopyrrolopyrrole-based polymers. Additionally, this class of ambipolar polymers also shows promise for complementary-like inverters with a high gain value of 163.
ABSTRACT
Long distance spin transport and photoresponse are demonstrated in a single F16 CuPc spin valve. By introducing a low-temperature strategy for controlling the morphology of the organic layer during the fabrication of a molecular spin valve, a large spin-diffusion length up to 180 nm is achieved at room temperature. Magnetoresistive and photoresponsive signals are simultaneously observed even in an air atmosphere.
Subject(s)
Semiconductors , Electrodes , Indoles/chemistry , Magnetics , Microscopy, Atomic Force , Microscopy, Electron, Scanning Transmission , Organometallic Compounds/chemistry , Quantum Theory , Spectrometry, X-Ray Emission , TemperatureABSTRACT
A diruthenium complex capped with two triphenylamine units was polymerized by electrochemical oxidation to afford metallopolymeric films with alternating diruthenium and tetraphenylbenzidine structures. The obtained thin films feature rich redox processes associated with the reduction of the bridging ligands (tetra(pyrid-2-yl)pyrazine) and the oxidation of the tetraphenylbenzidine and diruthenium segments. The sandwiched ITO/polymer film/Al electrical devices show excellent resistive memory switching with a low operational voltage, large ON/OFF current ratio (100-1000), good stability (500 cycles tested), and long retention time. In stark contrast, devices with polymeric films of a related monoruthenium complex show poor memory performance. The mechanism of the field-induced conductivity of the diruthenium polymer film is rationalized by the formation of a charge transfer state, as supported by DFT calculations.
ABSTRACT
In this article, a versatile 2-D conjugated polymer, PNDTP-DPP, containing alkylphenyl substituted naphthodithiophene is synthesized and characterized. PNDTP-DPP exhibits good solubility and crystallinity with a π-π stacking distance of ≈3.7 Å. Investigation of polymer solar cells (PSCs) and organic field-effect transistors (OFET) demonstrates a promising power conversion efficiency (PCE) of 4.11% and a high hole mobility of up to 0.86 cm(2) V(-1) s(-1) , so this is one of the few examples of versatile polymers that show both good field-effect mobility and PCE.
Subject(s)
Alkanes/chemistry , Naphthalenes/chemistry , Phenol/chemistry , Semiconductors , Thiophenes/chemistry , Microscopy, Atomic Force , Models, Chemical , Molecular Structure , Naphthalenes/chemical synthesis , Solar Energy , Spectrophotometry , Temperature , Thermogravimetry , Thiophenes/chemical synthesis , Transistors, Electronic , X-Ray DiffractionABSTRACT
The controlled fabrication of single-crystal twelve-pointed graphene grains is demonstrated for the first time by ambient pressure chemical vapor deposition on a liquid Cu surface. An edge-diffusion limited mechanism is proposed. The highly controllable growth of twelve-pointed graphene grains presents an intriguing case for the fundamental study of graphene growth and should exhibit wide applications in graphene-based electronics.
