The Larger Acenes: Versatile Organic Semiconductors

Anthony, John E.

doi:10.1002/anie.200604045

Cited by 1,955 publications

(1,286 citation statements)

References 419 publications

(415 reference statements)

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“…Considerable research efforts have been devoted to organic field-effect transistors last decades for the possibility of low-cost alternatives of silicon electronics, [1][2][3] and there has been enormous progress in developing organic semiconductors, where the best performance exceeds amorphous silicon transistors (a-SI). [4][5][6][7][8] Along with improving device performance, underlying charge transport mechanism has been extensively studied because it is closely related to device key parameters such as mobility, threshold voltage, subthreshold swing, and electrical and environmental stability.…”

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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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: 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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“…Acenes ( Fig. 1) and their derivatives are a typical organic semiconductor material that is being intensively studied (1)(2)(3)(4). With the increase of the oligomer length, the acenes display a rapid evolution of electronic structure and molecular properties, which greatly attracts the scientific community.…”

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Nature of ground and electronic excited states of higher acenes

Yang

Davidson

Yang

2016

Proc. Natl. Acad. Sci. U.S.A.

174

208

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Higher acenes have drawn much attention as promising organic semiconductors with versatile electronic properties. However, the nature of their ground state and electronic excited states is still not fully clear. Their unusual chemical reactivity and instability are the main obstacles for experimental studies, and the potentially prominent diradical character, which might require a multireference description in such large systems, hinders theoretical investigations. Here, we provide a detailed answer with the particleparticle random-phase approximation calculation. The 1 A g ground states of acenes up to decacene are on the closed-shell side of the diradical continuum, whereas the ground state of undecacene and dodecacene tilts more to the open-shell side with a growing polyradical character. The ground state of all acenes has covalent nature with respect to both short and long axes. The lowest triplet state 3 B 2u is always above the singlet ground state even though the energy gap could be vanishingly small in the polyacene limit. The bright singlet excited state 1 B 2u is a zwitterionic state to the short axis. The excited 1 A g state gradually switches from a doubleexcitation state to another zwitterionic state to the short axis, but always keeps its covalent nature to the long axis. An energy crossing between the 1 B 2u and excited 1 A g states happens between hexacene and heptacene. Further energetic consideration suggests that higher acenes are likely to undergo singlet fission with a low photovoltaic efficiency; however, the efficiency might be improved if a singlet fission into multiple triplets could be achieved.higher acenes | diradical | double excitation | particle-particle random-phase approximation | charge-transfer excitation

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“…Organic semiconductors have been studied for applications in light-emitting diodes, photovoltaics, field effect transistors, chemical sensors, and flexible displays. [1][2][3][4][5][6][7][8][9][10][11] The design and implementation of these materials requires a fundamental understanding of their physical properties. The transport of charge carriers (electrons or holes), in particular, is a key component of device performance.…”

mentioning

confidence: 99%

Temperature dependent c-axis hole mobilities in rubrene single crystals determined by time-of-flight

Pundsack

Haugen

Johnstone

et al. 2015

Applied Physics Letters

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Hole mobilities (μ) in rubrene single crystals (space group Cmca) along the crystallographic c-axis have been investigated as a function of temperature and applied electric field by the time-of-fight method. Measurements demonstrate an inverse power law dependence on temperature, namely, μ=μ0T−n with n = 1.8, from room temperature down to 180 K. At 296 K, the average value of μ was found to be 0.29 cm2/Vs increasing to an average value of 0.70 cm2/Vs at 180 K. Below 180 K a decrease in mobility is observed with further cooling. Overall, these results confirm the anisotropic nature of transport in rubrene crystals as well as the generality of the inverse power law temperature dependence that is observed for field effect mobility measurements in the a-b crystal plane.

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The Larger Acenes: Versatile Organic Semiconductors

Cited by 1,955 publications

References 419 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

Nature of ground and electronic excited states of higher acenes

Temperature dependent c-axis hole mobilities in rubrene single crystals determined by time-of-flight

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