Contact resistance and electrode material dependence of air-stable n-channel organic field-effect transistors using dimethyldicyanoquinonediimine (DMDCNQI)

Wada, Hiroshi; Shibata, K.; Bando, Yoshimasa; Mori, Takehiko

doi:10.1039/b808435a

Cited by 40 publications

(40 citation statements)

References 44 publications

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“…49,50 Contact effect is sometimes important in two-probe organic transistors. Contact resistance of DMDCNQI transistors has been estimated to be 100 k cm by the transfer line method, 40 and is much smaller than the channel resistance which amounts to more than 1000 k cm. Accordingly, contact resistance of DMDCNQI transistors is relatively small.…”

Section: Variable Temperature Characteristicsmentioning

confidence: 99%

“…Cy-NDI shows outstanding performance among the n-channel materials, with the reported mobility of 6.2 cm 2 /Vs due to the good thin-film morphology and the highly symmetrical brickwork packing of the planar molecules. 39 A small-molecule organic electron acceptor, DMDCNQI, forms air-stable n-channel transistors, 40,41 and recently, improved performance has been attained (μ = 0.23 cm 2 /Vs, on/off ratio = 2 × 10 6 , V T = 0 V) using the low vacuum evaporation method, though the threshold voltage is more susceptible to the surface treatment due to the trap states induced during the low vacuum evaporation. 42 In order to study the trap states, we have investigated the characteristics of these transistors in the temperature range between 260 K and 200 K. From the Arrhenius plot of the transconductance measured at low temperatures, we have studied gate voltage (V G ) dependence of the activation energy (E A ), and extracted the trap DOS from Lang's method, 33 as well as another method based on the E A vs. log V G plot.…”

Section: Introductionmentioning

confidence: 99%

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Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

et al. 2013

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We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N ’-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical VG above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge

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Section: Variable Temperature Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

et al. 2013

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“…Highly doped n-type silicon wafers with thermally grown silicon dioxide layers of 300 nm thickness were treated with polystyrene (PS) and hexamethyldisilazane (HMDS). 50,51 In addition, bare SiO 2 surface was investigated; in order to investigate particularly OH enhanced substrate, the substrate was used after the ultraviolet irradiation (Technovision model 208). The capacitance of the gate dielectric was C = 13.7 nF/cm 2 .…”

Section: Methodsmentioning

confidence: 99%

Analysing organic transistors based on interface approximation

Akiyama

Mori

2014

AIP Advances

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Temperature-dependent characteristics of organic transistors are analysed thoroughly using interface approximation. In contrast to amorphous silicon transistors, it is characteristic of organic transistors that the accumulation layer is concentrated on the first monolayer, and it is appropriate to consider interface charge rather than band bending. On the basis of this model, observed characteristics of hexamethylenetetrathiafulvalene (HMTTF) and dibenzotetrathiafulvalene (DBTTF) transistors with various surface treatments are analysed, and the trap distribution is extracted. In turn, starting from a simple exponential distribution, we can reproduce the temperature-dependent transistor characteristics as well as the gate voltage dependence of the activation energy, so we can investigate various aspects of organic transistors self-consistently under the interface approximation. Small deviation from such an ideal transistor operation is discussed assuming the presence of an energetically discrete trap level, which leads to a hump in the transfer characteristics. The contact resistance is estimated by measuring the transfer characteristics up to the linear region.

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“…46 Since metal complexes exhibit a wide variety of redox potentials, several metal complexes are excellent electron acceptors. Some metal complexes show n-channel performance, though others show p-channel performance.…”

Section: ¹1mentioning

confidence: 99%

“…(TTF)(TCNQ) electrodes also work well in n-channel transistors based on DM-DCNQI and F 16 CuPc. 46,69 In the latter case, we have constructed ambipolar transistors using a heterostructure consisting of a double layer of CuPc and F 16 CuPc. In the former case, the expected order of the electrode metal dependence is Ag > Cu > Au, but the actually observed one is Au > (TTF)(TCNQ) > Ag > Cu.…”

Section: ç Charge-transfer Complexes As Electrodesmentioning

confidence: 99%

Organic Charge-transfer Salts and the Component Molecules in Organic Transistors

Mori

2011

Chemistry Letters

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Electron donors and acceptors such as tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ), which have been long known as components of organic metals, act as p-and n-channel organic semiconductors in organic field-effect transistors. High performance, good thin-film properties, and long-term stability have been achieved on the basis of appropriate molecular design. In addition, their charge-transfer complexes work as the active layers as well as conducting electrode materials showing low contact resistance.

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Contact resistance and electrode material dependence of air-stable n-channel organic field-effect transistors using dimethyldicyanoquinonediimine (DMDCNQI)

Cited by 40 publications

References 44 publications

Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

Analysing organic transistors based on interface approximation

Organic Charge-transfer Salts and the Component Molecules in Organic Transistors

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