High‐Performance n‐ and p‐Type Single‐Crystal Organic Transistors with Free‐Space Gate Dielectrics

Menard, Etienne; Podzorov, Vitaly; Hur, Seung Hyun; Gaur, Anshu; Gershenson, M. E.; Rogers, John A.

doi:10.1002/adma.200401017

Cited by 455 publications

(377 citation statements)

References 20 publications

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“…Band transport is one of the most important challenges in organic transistors, so it has been intensively investigated in single-crystal transistors. [9][10][11][12] …”

Section: Band Transportmentioning

confidence: 99%

“…Charge transport of organic transistors using single crystals and thin-films has been studied from temperature (T)-dependent transistor characteristics. Intrinsic carrier transport, in particular, band transport, has been explored in organic single crystals, [9][10][11][12] and trap-limited charge transport has been examined in organic thin films, which have higher density of trap states due to the structural defect, grain boundaries, and chemical impurities. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The multiple trapping and release model for a Author to whom correspondence should be addressed.…”

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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“…Band transport is one of the most important challenges in organic transistors, so it has been intensively investigated in single-crystal transistors. [9][10][11][12] …”

Section: Band Transportmentioning

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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“…For the estimate of µ, we have used the capacitance calculated from the device geometry; this value is consistent with the direct measurements of C i in the test structures formed by lamination of the stamp against a metallic surface [9]. This definition of µ assumes that all charge carriers with the…”

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confidence: 97%

“…Application of a novel experimental technique based on the "air-gap" transistor stamps [9] allowed realization of a high room-temperature mobility for p-type carriers (~20 cm 2 /Vs). Two signatures of the intrinsic transport, -the mobility increase with decreasing temperature and the mobility anisotropy, have been observed in the temperature range ~150 -300 K. At lower temperatures, where the charge transport is dominated by shallow traps, the mobility decreases exponentially with cooling and anisotropy of µ vanishes.…”

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confidence: 99%

Intrinsic Charge Transport on the Surface of Organic Semiconductors

et al. 2004

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The novel technique based on air-gap transistor stamps enabled realization of the intrinsic (not dominated by static disorder) transport of the electric-field-induced charge carriers on the surface of rubrene crystals over a wide temperature range. The signatures of the intrinsic transport are the anisotropy of the carrier mobility, µ, and the growth of µ with cooling. The anisotropy of µ vanishes in the activation regime at lower temperatures, where the charge transport becomes dominated by shallow traps. The deep traps, deliberately introduced into the crystal by X-ray radiation, increase the field-effect threshold without affecting the mobility. These traps filled above the field-effect threshold do not scatter the mobile polaronic carriers.

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“…8 In previous studies, we successfully measured the Hall effect in organic semiconductors using rubrene single-crystal transistors, 3,5 which are well known to be the highest performing organic transistors at room temperature, with a mobility above 20 cm 2 Vs − 1 . [9][10][11] The experiment showed precise measurements for the band-transport relation, that is, R H = 1/Q, indicating coherent electronic states. Subsequently, materials as dinaphtho[2,3-b:2',3'-f]thieno [3,2-b] thiophene (DNTT), alkylated DNTT, pentacene derivatives and N,N'-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN 2 ) turned out to satisfy the same condition, and coherent band transport was observed at room temperature.…”

Section: Introductionmentioning

confidence: 99%

The emergence of charge coherence in soft molecular organic semiconductors via the suppression of thermal fluctuations

et al. 2016

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Organic semiconductors are already widely used in electronics. Nevertheless, their fundamental properties are still being debated. In particular, charge transport, which determines the performance of organic light-emitting diodes, solar cells and organic field-effect transistors, has been described by a wide range of complementary but incompatible theories. These theories involve either localized charge carriers hopping from molecule to molecule, leading to incoherent charge transport, or delocalized charge carriers moving around freely in the semiconductor, leading to coherent transport. In this communication, we reveal the first experimental evidence that charge coherence can be tuned from partially to fully coherent in one and the same material -pentacene-showing a continuous transition from one transport mechanism to the other. Microscopically, the transport mechanism depends on the overlap of adjacent molecular orbitals, which in turn is sensitive to molecular thermal fluctuations. We control these fluctuations through moderate variations of pressure and temperature, leading to a mobility increase of 75%. We quantify the influence of these thermal fluctuations by estimating the critical value below which fully coherent charge transport emerges. The ability to control thermal fluctuations and therefore to effectively tune the charge coherence is an important key to improving charge transport in soft molecular materials. INTRODUCTIONHistorically, the existence of coherent electronic states in weakly van der Waals bonded crystals has been a controversial topic. 1 The weak intermolecular interaction leads to a strong thermal vibration of each molecule, resulting in the dynamic disorder of the crystal lattice. Dynamic disorder subsequently leads to a complex interaction between the soft lattice and the charge carriers, which is unique to these systems. In classical semiconductors, the charge transport mechanism can be directly determined from the temperature dependence of the mobility. In an organic semiconductor, however, the temperature dependence of the mobility does not necessarily reveal the nature of the charge transport and therefore it cannot be determined whether a system is described by the short-range hopping of localized charge carriers or band transport due to extended electronic wavefunctions. 2 For this reason, a more direct method is required to study the nature of charge transport in these systems. The Hall effect is such a method, as it is directly connected to the coherence of the charge carrier wavefunction via interaction with the applied magnetic field. The quantum mechanical origin of this interaction lies in the coupling of the wave number k of the delocalized charge carrier wavefunction with the vector potential A of the magnetic field.

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High‐Performance n‐ and p‐Type Single‐Crystal Organic Transistors with Free‐Space Gate Dielectrics

Cited by 455 publications

References 20 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

Intrinsic Charge Transport on the Surface of Organic Semiconductors

The emergence of charge coherence in soft molecular organic semiconductors via the suppression of thermal fluctuations

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