Field dependence of hole mobility in TPD-doped polystyrene

Mohan, S. Raj; Joshi, M. P.

doi:10.1016/j.ssc.2006.05.020

Cited by 18 publications

(17 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The measured and V T values obtained for pTPD are consistent with results reported for OTFTs measured in ambient conditions and deposited on a SiO 2 dielectric layer ͑reported field-effect mobilities between 10 −5 and 10 −4 cm 2 / V s͒. [12][13][14] The possibility of improving the mobility of such materials has been demonstrated and reported using various approaches. 7,8,[12][13][14][15] For example, it is possible to modify the polymer chain by anchoring end-capping groups, 12 to use them as dopant for inert polymers such as polystyrene or polycarbonate, 7,13,14 or to oxidize the arylamines with strong oxidant molecules such as ClO 4 − and AgSbF 6 .…”

supporting

confidence: 85%

“…[12][13][14] The possibility of improving the mobility of such materials has been demonstrated and reported using various approaches. 7,8,[12][13][14][15] For example, it is possible to modify the polymer chain by anchoring end-capping groups, 12 to use them as dopant for inert polymers such as polystyrene or polycarbonate, 7,13,14 or to oxidize the arylamines with strong oxidant molecules such as ClO 4 − and AgSbF 6 . 8, 15 Recently, Bolink et al 6,16 have shown that pTPD properties can be modified by oxidizing it with a molecular magnetic cluster ͓Mn 12 O 12 ͑H 2 O͒ 4 ͑C 6 F 5 COO͒ 16 ͔.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet

Cheylan

Puigdollers

Bolink

et al. 2008

Journal of Applied Physics

View full text Add to dashboard Cite

Thin film transistors based on polyarylamine poly͑N , NЈ-diphenyl-N , NЈbis͑4-hexylphenyl͒-͓1,1Јbiphenyl͔-4,4Ј-diamine ͑pTPD͒ were fabricated using spin coating in order to measure the mobility of pTPD upon oxidation. Partially oxidized pTPD with a molecular magnetic cluster showed an increase in mobility of over two orders of magnitude. A transition in the mobility of pTPD upon doping could also be observed by the presence of a maximum obtained for a given oxidant ratio and subsequent decrease for a higher ratio. Such result agrees well with a previously reported model based on the combined effect of dipolar broadening of the density of states and transport manifold filling. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2917304͔In recent years, there have been increasing interests and research activities in the field of organic light-emitting devices ͑OLEDs͒. The promise of the use of this technology in flat panel displays through the fabrication of low-cost and flexible electronic devices has been the main driving force. Although enormous progress has been achieved in improving the luminance efficiency, color fidelity, and device lifetime, there is a continuous effort for a better stability of the device toward commercialization. Interface engineering between the electrodes and the emitting layer is important for the improvement of the device lifetime as well as luminous efficiency in OLEDs and has lead to the fabrication of multilayer devices, with charge transport and charge injection layer ͑HIL͒ deposited by vacuum sublimation technique. 1,2 In terms of solution processable OLEDs, such as polymer based light emitting devices ͑PLEDs͒, the use of a PEDOT-PSS layer as the HIL is well known to improve the hole injection from the indium tin oxide ͑ITO͒ as well as planarizing the ITO surface and has been well studied. 3,4 Although it has shown improved device performance such as lower operational voltage and higher luminance efficiency, other problems render it not suitable for device stability. For example, it is found that the ITO/PEDOT-PSS interface is not stable due to the etching of ITO by the strong acidic nature of PSS. 5 Therefore, at this stage of PLED development, the search for other better solution processable HIL material is needed and it is much required to modify the HIL to further improve the device lifetime as well as its efficiency. Following such an approach, recent results by Bolink et al. 6 have shown that a solution processable HIL material can be used for PLEDs and showed improved performance as when using PEDOT-PSS. Such HIL material is based on a polyarylamine poly͑N , NЈ-diphenyl-N , NЈbis͑4-hexylphenyl͒-͓1,1Јbiphenyl͔-4,4Ј-diamine ͑pTPD͒ which was doped with a molecular magnet and showed tunable conductivity depending on the level of doping. The diamine derivative pTPD resembles very closely to the well known and intensively used organic molecule N , NЈ-diphenyl-N , NЈbis͑3-methylphenyl͒-͓1,1Јbiphenyl͔-4,4Ј-diamine ͑TPD͒, while being processable by the spin coating technique and...

show abstract

supporting

confidence: 85%

mentioning

confidence: 99%

Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet

Cheylan

Puigdollers

Bolink

et al. 2008

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…However, at high electric fields, those favorable paths whose direction is not aligned with the direction of external electric field will be eliminated, resulting in lower drift mobility. 27 The field-assisted barrier lowering becomes significant at higher fields and competes with the fieldinduced elimination of favorable routes. Positional and energetic disorder thus acting in the opposing way will lead to the disappearance of the field dependence of mobility at particular field strength.…”

Section: Resultsmentioning

confidence: 99%

Ambipolar charge transport in bulk heterojunction of poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene)∕C60 composite

Quan-Min

Hou

Jin

et al. 2007

Journal of Applied Physics

View full text Add to dashboard Cite

Using the time-of-flight technique (TOF), the influence of C60 concentrations on ambipolar charge transport in poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV)∕C60 composite has been investigated. Adding C60 to the blend increases both electron and hole mobilities, compared to the pristine polymer. In the pristine MEH-PPV, the mobility of electrons is below the measurable range. However, electron mobility (10−7 cm2 V−1 s−1) could be calculated when the weight ratio of C60: MEH-PPV increased to 1:18. The temperature and electric field dependence of mobility is analyzed in the disorder formalism. It is observed that above ∼290 K the slope of the electric field dependence of the electron mobility becomes negative. The occurrence of negative field dependence in composite samples is attributed to the large positional disorder (Σ=4).

show abstract

“…Provided σ P is not dependent upon the internal structure of the dopant dipoles, the relative locations of the DOS characteristics given in Figure 5 (where σ P = 0) remain invariant, however, and the detection of agglomeration is still possible. Polystyrene based MDPs offer a promising opportunity to study agglomeration effects as they provide a relatively low σ P background and appear to induce clustering of small dopant molecules such as TPD [11].…”

Section: Experimental Molecularly Doped Polymer Datamentioning

confidence: 99%

“…Local ordering is likely to arise as a result of dipole-dipole interactions that result in molecular agglomeration and crystallisation [9][10][11][12]. Under these circumstances the ability of the GDM model to parameterise the associated hopping transport may be compromised.…”

Section: Introductionmentioning

confidence: 99%

The Sensitivity of Hopping Transport in Dipolar Glasses and Molecularly Doped Polymers to Localised Dipole Ordering

Goldie¹

2012

MATERIALS

View full text Add to dashboard Cite

The influence of ordered dipole regions upon hopping transport through dipolar glasses and molecularly doped polymers has been evaluated via Monte Carlo simulation. Ordered dipole regions were introduced as a set of randomly distributed cubes throughout disordered dipolar lattices where the number and size of the cubes could be independently varied. Within each cube neighbouring dipoles were anti-aligned to minimise the local energetic disorder but the specific dipole orientation for each inserted cube was randomly selected. Whilst the underlying density of states appears to become energetically narrower as the overall proportion of disordered dipole sites is diluted by inserted ordered cubes this is not generally reflected in the associated transport properties. It is demonstrated that the lattice potential that is associated with background non-aligned dipoles in dipolar glasses have a controlling influence upon the observed macroscopic mobility. Confirmation of the importance of such non-aligned dipoles is provided by complimentary simulations using molecularly doped polymers where the dopant dipoles are agglomerated and ordered into cubic regions. The implication of the simulation results for the interpretation of experimental transport data in dipolar glasses and molecularly doped polymers is evaluated.

show abstract

Field dependence of hole mobility in TPD-doped polystyrene

Cited by 18 publications

References 18 publications

Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet

Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet

Ambipolar charge transport in bulk heterojunction of poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene)∕C60 composite

The Sensitivity of Hopping Transport in Dipolar Glasses and Molecularly Doped Polymers to Localised Dipole Ordering

Contact Info

Product

Resources

About