Carrier density dependence of mobility in organic solids: A Monte Carlo simulation

Zhou, Jin; Zhou, Yang; Zhao, Jinbin; Wu, Chenming; Ding, Xinyi; Hou, Xiaoyuan

doi:10.1103/physrevb.75.153201

Cited by 108 publications

(81 citation statements)

References 20 publications

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“…Assuming incoherent hopping of charge carriers between localized states and using advanced three-dimensional (3D) mechanistic modeling techniques, it is now possible to predict the macroscopic charge transport properties of organic semiconductors using microscopic information at the molecular level, including a Gaussian distribution of site energies, the spatial packing of the material, the distribution of charge transfer integrals, and the reorganization energies [5][6][7][8][9][10][11][12]. Device modeling has been carried out using drift-diffusion [13][14][15][16][17][18], master-equation (ME) [19][20][21][22][23], and kinetic Monte Carlo (KMC) [2,[24][25][26][27][28] simulation methods. Within driftdiffusion and ME device simulations, the Coulomb interaction between the charge carriers is treated using a mean-field approach: using the Poisson equation, the (time-averaged) charge density is used to calculate the (time-averaged) electric field due to the space charge in the device.…”

Section: Introductionmentioning

confidence: 99%

Effect of Coulomb correlation on charge transport in disordered organic semiconductors

Liu

Eersel²,

et al. 2017

Phys. Rev. B

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Charge transport in disordered organic semiconductors, which is governed by incoherent hopping between localized molecular states, is frequently studied using a mean-field approach. However, such an approach only considers the time-averaged occupation of sites and neglects the correlation effect resulting from the Coulomb interaction between charge carriers. Here, we study the charge transport in unipolar organic devices using kinetic Monte Carlo simulations and show that the effect of Coulomb correlation is already important when the charge-carrier concentration is above 10 −3 per molecular site and the electric field is smaller than 10 8 V/m. The mean-field approach is then no longer valid, and neglecting the effect can result in significant errors in device modeling. This finding is supported by experimental current density-voltage characteristics of ultrathin sandwich-type unipolar poly(3-hexylthiophene) (P3HT) devices, where high carrier concentrations are reached.

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Section: Introductionmentioning

confidence: 99%

Effect of Coulomb correlation on charge transport in disordered organic semiconductors

Liu

Eersel²,

et al. 2017

Phys. Rev. B

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“…For the GDM, expressions for the mobility function have been obtained from semianalytical, [8][9][10][11][12] three-dimensional master equation ͑3D-ME͒, 13 and Monte Carlo calculations. 7,14 In a limited field range, the field dependence of the mobility is then well described by the Poole-Frenkel ͑PF͒ type expression ͑F͒ ϰ exp͑␥ ͱ F͒, 15,16 which is used more conventionally in analyzes of transport in OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Hole transport in the organic small molecule material α-NPD: evidence for the presence of correlated disorder

Mensfoort

Shabro²,

Vries

et al. 2010

Journal of Applied Physics

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In this paper the hole mobility in the amorphous small molecule material N,NЈ-bis͑1-naphthyl͒-N,NЈ-diphenyl-1 , 1Ј-biphenyl-4 , 4Ј-diamine ͑␣-NPD͒, which is frequently used in organic light-emitting diodes, is studied. From an analysis of the temperature and layer thickness dependence of the steady-state current density in sandwich-type ␣-NPD-based hole-only devices, it is found that a conventional mobility model assuming a Poole-Frenkel type field dependence and neglecting the carrier density dependence is not appropriate. Consistent descriptions with equal quality are obtained within the framework of two forms of the Gaussian disorder model ͑GDM and CDM͒, within which the presence of energetic disorder is described by a Gaussian density of states and within which spatial correlations between the site energies are absent or are included, respectively. Both models contain a carrier density dependence of the mobility. Based on a comparison of the site densities as obtained from both models with the molecular density, we argue that the analysis provides evidence for the presence of correlated disorder.

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“…The (1 − P i ) excludes, in a mean-field approximation, 27 the possibility of double occupancy. We ignored the Coulomb interaction between carriers in different sites since it was shown by Zhou et al 28 that for low-carrier densities, such as the ones considered in this work, this effect is negligible.…”

Section: Modelmentioning

confidence: 99%

Charge carrier mobility in a two-phase disordered organic system in the low-carrier concentration regime

Woellner

Freire

et al. 2013

Phys. Rev. B

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In this paper we use a three-dimensional Pauli master equation to investigate the charge carrier mobility of a two-phase system which can mimic donor-acceptor and amorphous-crystalline bulk heterojunctions. By taking the energetic disorder of each phase, their energy offset, and domain morphology into consideration, we show that the carrier mobility can have a completely different behavior when compared to a one-phase system. When the energy offset is equal to zero, the mobility is controlled by the more disordered phase. When the energy offset is nonzero, we show that the mobility electric field dependence switches from negative to positive at a threshold field proportional to the energy offset. Additionally, the influence of morphology, through the domain size and volume ratio parameters, on the transport is investigated and an approximate analytical expression for the zero field mobility is provided.

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Carrier density dependence of mobility in organic solids: A Monte Carlo simulation

Cited by 108 publications

References 20 publications

Effect of Coulomb correlation on charge transport in disordered organic semiconductors

Effect of Coulomb correlation on charge transport in disordered organic semiconductors

Hole transport in the organic small molecule material α-NPD: evidence for the presence of correlated disorder

Charge carrier mobility in a two-phase disordered organic system in the low-carrier concentration regime

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