Semiconductors In Organic Field-effect Transistors Research Articles

Phenoxazine-Based Conjugated Polymers: A New Class of Organic Semiconductors for Field-Effect Transistors

Five new phenoxazine-based conjugated polymers, including poly(10-hexylphenoxazine-3,7-diyl), poly(10-hexylphenoxazine-3,7-diyl-alt-9,9-dihexyl-2,7-fluorene), and poly(10-hexylphenoxazine-3,7-diyl-alt-3-hexyl-2,5-thiophene), were synthesized, characterized, and successfully used as p-channel semiconductors in organic field-effect transistors. The polymers have high glass transition temperatures in the 112−230 °C range. The phenoxazine-based polymers have low ionization potentials or high-lying HOMO levels (4.8−4.9 eV), which were estimated from cyclic voltammetry. Organic field-effect transistors based on the phenoxazine polymer semiconductors have a field effect hole mobility of up to 6 × 10-4 cm2/(V s) and an on/off ratio of up to 104. These results demonstrate that phenoxazine-based conjugated polymers are promising p-type semiconductors for solution processable thin film transistors.

Recent progress and future prospect of organic semiconductors for field-effect transistors

Recent progress and future prospect of organic semiconductors for field-effect transistors

A General Synthetic Approach to Novel Bis(tetracenyl) Aromatics for OFET Application

AbstractA molecular tool box is presented, allowing the efficient synthesis of a broad variety of bis(tetracenyl) aromatics. These materials might be of considerable interest as semiconductors in organic field-effect transistors. The general synthetic strategy applied here involves Diels-Alder reactions of bromobenzocyclobutene derivatives and arene-1,4-endoxides[1], followed by transition-metal catalyzed condensation reactions of the formed 9-bromo-6,11-dihydrotetracene derivatives with aryldiboronic and -stannyl derivatives, respectively. In the final step, the resulting bis(dihydrotetracenyl) derivatives were dehydrogenated, giving the bis(tetracenyl) aromatics in good yields. They were characterized using NMR, UV-vis and mass spectrometry. Moreover, for some of these semiconductors the charge carrier mobility in thin film transistors has been determined.

Perfluoropentacene: high-performance p-n junctions and complementary circuits with pentacene.

We report the synthesis and characterization of perfluoropentacene as an n-type semiconductor for organic field-effect transistors (OFETs). Perfluoropentacene is a planar and crystalline material that adopts a herringbone structure as observed for pentacene. OFETs with perfluoropentacene were constructed using top-contact geometry, and an electron mobility of 0.11 cm2 V-1 s-1 was observed. Bipolar OFETs with perfluoropentacene and pentacene function at both negative and positive gate voltages. The improved p-n junctions are probably due to the similar d-spacings of both acenes. Complementary inverter circuits were fabricated, and the transfer characteristics exhibit a sharp inversion of the output signal with a high-voltage gain.

2,6-Diphenylbenzo[1,2-b:4,5-b']dichalcogenophenes: a new class of high-performance semiconductors for organic field-effect transistors.

2,6-Diphenylbenzo[1,2-b:4,5-b']dichalcogenophenes including thiophene, selenophene, and tellurophene analogues as organic semiconductors for field-effect transistors were effectively synthesized in three steps from commercially available 1,4-dibromobenzene. All three benzodichalcogenophenes acted as good p-type semiconductors, and particularly the selenophene analogue, 2,6-diphenylbenzo[1,2-b:4,5-b']diselenophene, showed high FET mobility of 0.17 cm2 V-1 s-1.

Study on the corner effect in new grooved-gate nMOSFET

The function and influence of the corner effect in groovedgate MOSFET is simulated using classical twodimensional device simulator PISCESⅡ. The electric field of the channel in groovedgate metalorganic semiconductor field effect transistor(MOSFET) and impact on the threshold and hot carrier effect are studied. The corner effect is very favorable to suppressing short channel effects and hot carrier effects. The impact of corner effect on groovedgate MOSFET is changed with the change of the corner, and is the largest at about 45°. Therefore， the groovedgate MOSFET has a very great application prospect in deep submicro device architecture.

Potentiometry of an operating organic semiconductor field-effect transistor

The potential profile across the channel of an operating sexithiophene-based field-effect transistor (FET) was investigated using an atomic force microscope with a conducting probe. A high impedance electrometer recorded the probe potential when it was placed in contact at fixed points with the channel surface. Tapping mode images taken with the same probe before and after individual point contact measurements verified that no damage was done to the device and allowed correlation of the potential profile with the device architecture. For any given source-drain bias, most of the potential drop occurred at the source and drain contacts, meaning the FET was contact limited. Moreover, the potential drop was not fixed but depended on the applied drain and gate voltages. This study demonstrates the utility of potential profiling for identifying high resistance bottlenecks to charge transport in organic-based devices.