Mobility of charge carriers in vapor-phase grown C60 single crystal

Frankevich, E. L.; Maruyama, Yusei; Ogata, Hironori

doi:10.1016/0009-2614(93)85452-t

Cited by 148 publications

(104 citation statements)

References 15 publications

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“…This experiment provides unambiguous test for the suggested model because energetic disorder effects are expected to dominate the thermally activated transport in C 60 owing to the smallest electron-phonon coupling in this material 22 among other aromatic molecular systems, that is also supported by the almost temperature-independent charge mobility in C 60 single crystals. 23 We show that the MNR effect for the OFET mobility experimentally observed before for other organic semiconductors can also be well interpreted by the present theory. Besides, for completeness sake, the suggested theoretical formalism was also extended down to very low temperatures and a Mott-type charge carrier hopping regime has been reproduced in such case.…”

Section: Introductionsupporting

confidence: 85%

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

et al. 2010

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Temperature-activated charge transport in disordered organic semiconductors at large carrier concentrations, especially relevant in organic field-effect transistors ͑OFETs͒, has been thoroughly considered using a recently developed analytical formalism assuming a Gaussian density-of-states ͑DOS͒ distribution and MillerAbrahams jump rates. We demonstrate that the apparent Meyer-Neldel compensation rule ͑MNR͒ is recovered regarding the temperature dependences of the charge carrier mobility upon varying the carrier concentration but not regarding varying the width of the DOS. We show that establishment of the MNR is a characteristic signature of hopping transport in a random system with variable carrier concentration. The polaron formation was not involved to rationalize this phenomenon. The MNR effect has been studied in a OFET based on C 60 films, a material with negligible electron-phonon coupling, and successfully described by the present model. We show that this phenomenon is entirely due to the evolution of the occupational DOS profile upon increasing carrier concentration and this mechanism is specific to materials with Gaussian-shaped DOS. The suggested model provides compact analytical relations which can be readily used for the evaluation of important material parameters from experimentally accessible data on temperature dependence of the mobility in organic electronic devices. Experimental results on temperature-dependent charge mobility reported before for organic semiconductors by other authors can be well interpreted by using the model presented in this paper. In addition, the presented analytical formalism predicts a transition to a Mott-type charge carrier hopping regime at very low temperatures, which also manifests a MNR effect.

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Section: Introductionsupporting

confidence: 85%

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

et al. 2010

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“…Owing to the small value of hRi the initial behavior might correspond to transport within short-range crystalline domains where the charge pairs are photogenerated. This hypothesis is supported by the comparable electron mobilities found in C 60 single crystals (0:5 cm 2 =V s) [29] and C 60 based transistors [30]. The dispersive regime is characterized by a dramatic mobility decrease.…”

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confidence: 67%

Photoinduced Transient Stark Spectroscopy in Organic Semiconductors: A Method for Charge Mobility Determination in the Picosecond Regime

et al. 2006

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Subpicosecond photoinduced Stark spectroscopy experiments are carried out for measuring charge carrier mobility in organic semiconductors. The technique is demonstrated in state-of-art devices based on methanofullerene. The transient mobility of photogenerated charge carriers is measured in the picosecond time domain. Electric field dependent mobility is observed from the earliest time scales. In addition, two distinct transport regimes are revealed: a short-lived state, approximately 10 ps, of high mobility and a transient towards the trap limited transport, associated with the mesoscopic structure of the medium. DOI: 10.1103/PhysRevLett.96.106601 PACS numbers: 72.80.Rj, 72.80.Ng, 78.47.+p, 78.66.Tr Charge carrier mobility in organic semiconductors is a critical material property that determines the performance characteristics of many electronic devices, including fieldeffect transistors [1], light-emitting diodes [2], and solar cells [3]. For this reason, many experimental techniques and theoretical modeling have been devoted to its measure and interpretation [4 -7]. It turns out that different experiments provide different values of carrier mobility in the same material, due to varying experimental conditions and different device architectures. For instance, it is found that the hole mobility of common polymer semiconductors is several orders of magnitude lower when tested in lightemitting diodes than in field-effect transistors [8,9]. Such variations make material evaluation difficult if not impossible.In amorphous organic materials charge carrier mobility is often the average of a number of slowing down processes where defects and traps dominate. Ideally one would like to measure the carrier mobility in a pure, defect free material, so meaningful comparison between different experiments and theory would be allowed. Close to this ideal case is the use of time resolved microwave conductivity technique, an electrodeless method that monitors charge dipoles absorption in the transient regime [7,10]. The time resolution of this technique is limited, however, to the nanosecond domain. Here we present an alternative approach, based on photoinduced transient Stark effect in which optical probing is exploited for extracting mobility values in the picosecond time regime. A related technique, exploiting the Franz-Keldysh effect in extended band states, was successfully employed by Shank et al. to measure nonequilibrium carrier transport in inorganic semiconductors [11][12][13]. The validity of our method relies on the fact that charge transport is monitored in situ on the compound without current extraction, avoiding pitfalls caused by carrier migration along macroscopic regions of the sample as well as by carrier extraction at semiconductor-metal electrode interfaces. Mobilities obtained in this way can be considered as upper limit values, unaffected by limiting processes such as trapping or recombination. This information is intrinsic and constitutes a direct feedback for the design of new materials with improved...

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“…Decay of the EA in pristine C 60 film within a few picoseconds is consistent with mobilities of the order of 1 cm 2 /(V·s) for both types of carriers. 30,31 Thus, free carriers are extracted from the C 60 film on the time-scale from few to several picoseconds at a field strength of about 0.5 MV/cm.…”

Section: Resultsmentioning

confidence: 99%

Dissociation of Charge Transfer States and Carrier Separation in Bilayer Organic Solar Cells: A Time-Resolved Electroabsorption Spectroscopy Study

Jonghe-Risse²,

et al. 2015

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Ultrafast optical probing of the electric field by means of Stark effect in planar heterojunction cyanine dye/fullerene organic solar cells enables one to directly monitor the dynamics of free electron formation during the dissociation of interfacial charge transfer (CT) states. Motions of electrons and holes is scrutinized separately by selectively probing the Stark shift dynamics at selected wavelengths. It is shown that only charge pairs with an effective electron−hole separation distance of less than 4 nm are created during the dissociation of Frenkel excitons. Dissociation of the coulombically bound charge pairs is identified as the major rate-limiting step for charge carriers' generation. Interfacial CT states split into free charges on the time-scale of tens to hundreds of picoseconds, mainly by electron escape from the Coulomb potential over a barrier that is lowered by the electric field. The motion of holes in the small molecule donor material during the charge separation time is found to be insignificant.

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Mobility of charge carriers in vapor-phase grown C60 single crystal

Cited by 148 publications

References 15 publications

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

Temperature dependence of the charge carrier mobility in disordered organic semiconductors at large carrier concentrations

Photoinduced Transient Stark Spectroscopy in Organic Semiconductors: A Method for Charge Mobility Determination in the Picosecond Regime

Dissociation of Charge Transfer States and Carrier Separation in Bilayer Organic Solar Cells: A Time-Resolved Electroabsorption Spectroscopy Study

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