Non-dispersive Hole Transport in a Soluble Poly(p-phenylene vinylene)

Inigo, Anto R.; Tan, C. H.; Fann, Wunshain; Huang, Y. S.; Perng, Gung-Yeong; Chen, S.-A.

doi:10.1002/1521-4095(200104)13:7<504::aid-adma504>3.0.co;2-o

Cited by 53 publications

(46 citation statements)

References 15 publications

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“…Since then, many efforts have been undertaken to improve their performance and place them as promising candidates to a wide range of applications, such as optoelectronic devices in flat panel and flexible displays [4,5]. Despite the increase in their importance and simultaneously-acquired knowledge, charge transport mechanisms have not been fully understood [6][7][8]. A detailed description of energy states and charge carrier mobility requires many efforts due to the difficulty in the use of conventional techniques such as Time-of-Flight (ToF) to study thin-films as in electronic devices [9,10].…”

Section: Introductionmentioning

confidence: 99%

Determination of carrier mobility in MEH-PPV thin-films by stationary and transient current techniques

Amorim

Cavallari

Santos

et al. 2012

Journal of Non-Crystalline Solids

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Charge transport and shelf-degradation of MEH-PPV thin-films were investigated through stationary (e.g. current versus voltage -JxV) and transient (e.g. Time-of-Flight -ToF, Dark-Injection Space-Charge-Limited Current -DI-SCLC, Charge Extraction by Linearly Increasing Voltage -CELIV) current techniques. Charge carrier mobility in nanometric films was best characterized through JxV and DI-SCLC. It approaches 10 − 6 cm 2 /Vs under a SCLC regime with deep traps for light-emitting diode applications. ToF measurements performed on micrometric layers (i.e.~3 μm) confirmed studies in 100 nm-thick films as deposited in OLEDs. All results were comparable to a similar poly(para-phenylene vinylene) derivative, MDMO-PPV. Electrical properties extracted from thin-film transistors demonstrated mobility dependence on carrier concentration in the channel (~10 − 7 -10 − 4 cm 2 /Vs). At low accumulated charge levels and reduced free carrier concentration, a perfect agreement to the previously cited techniques was observed. Degradation was verified through mobility reduction and changes in trap distribution of states.

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Section: Introductionmentioning

confidence: 99%

Determination of carrier mobility in MEH-PPV thin-films by stationary and transient current techniques

Amorim

Cavallari

Santos

et al. 2012

Journal of Non-Crystalline Solids

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“…5,6 This is a concern because the morphology and purity of the starting material strongly influence charge transport contributing to dispersion in the photocurrent transients. 7 While the effects of different solvents or casting technique on TOF measurements has been shown, 8 not much work exists in the literature regarding how measurement parameters and also environmental conditions in air or in controlled atmosphere can influence TOF measurements.…”

Section: Introductionmentioning

confidence: 99%

Space Charge and Carrier Trapping Effects on the Transient Photocurrents of Organic Materials Using the Time-of-Flight Technique

Cusumano

Gambino

2007

Journal of Elec Materi

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We apply the time-of-flight (TOF) technique to study space charge and carrier trapping effects in the organic materials N,N'-diphenyl-N,N'-bis(3- methylphenyl)-1,1-biphenyl-4,4'-diamine (TPD) and tris(8-hydroxyquinolato) aluminum (Alq3). This is carried out by changing the applied electric field, the laser pulse intensity, and the repetition rate together with environmental conditions in air or in vacuum. We report for the first time, to the best of our knowledge, a clearly nondispersive electron transport in TPD due to the absence of deep traps. Conversely, Alq3 exhibits a dispersive electron transport. However, this can be partially recovered by leaving the sample in high vacuum for several hours. This behavior is ascribed to a reduced concentration of O2-related deep traps

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“…hole mobility) characteristics. 3 Paradoxically, charge carrier mobility has been reported to vary greatly in films of MEH-PPV (a soluble derivative of poly (phenylenevinyle) having identical (far-field) photoluminescence (PL) spectra. 4 This suggests that local morphology, in terms of sub-micron domains, may play an important role in charge transport and photo-physics.…”

Section: Introductionmentioning

confidence: 63%

Development of a Controlled Environment Near‐Field Optical Microscope for Organic Thin Film Studies

Inigo

Fann

et al. 2010

J Chinese Chemical Soc

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The requirements of a microscope differ greatly from field to field and with the sample being studied. Organic thin films are highly sensitive to environmental conditions being rapidly photobleached in the presence of oxygen. In this paper we introduce the design of a low cost near field optical microscope suitable for environmentally controlled studies. We demonstrate that reducing ambient pressure to~10 mTorr (1.3 Pa) of nitrogen (a pressure accessible with a mechanical pump) significantly reduces photo-bleaching on a typical experimental timescale. In addition, we introduce a novel non-optical feedback control mechanism combining a piezoelectric diaphragm with a tuning fork. The morphology of thin films of MEH-PPV spin cast from the polymer dissolved in chlorobenzene is investigated. These films are shown to be featureless on a 100 nm length scale in terms of topology, PL intensity and PL spectrum both before and during photo-bleaching. As far as we are aware these are the first reported thin films of MEH-PPV grown in which~100 nm sized domains are absent. We believe that the ability to control environment will not only allow better optical characterization of thin films but also opens up the possibility of the production of novel two dimensional organic photonic crystals through a combination of mechanical disruption, photo-bleaching and photo-conjugation of polymers.

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Non-dispersive Hole Transport in a Soluble Poly(p-phenylene vinylene)

Cited by 53 publications

References 15 publications

Determination of carrier mobility in MEH-PPV thin-films by stationary and transient current techniques

Determination of carrier mobility in MEH-PPV thin-films by stationary and transient current techniques

Space Charge and Carrier Trapping Effects on the Transient Photocurrents of Organic Materials Using the Time-of-Flight Technique

Development of a Controlled Environment Near‐Field Optical Microscope for Organic Thin Film Studies

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