Hole and Electron Transport in Triarylamine-Based Charge-Transport Materials Investigated by the Time-of-Flight Method

Klenkler, Richard A.; Voloshin, Galina

doi:10.1021/jp2036586

Cited by 19 publications

(18 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has already been demonstrated that TOF can be used to measure the charge carrier mobility of solid-phase triarylamines. 27 In this study, TOF transients were captured using the technique described by Melnyk and Pai. 28 This method is based on measuring the time it takes for charges to travel through a layer of material of known thickness under a constant applied voltage.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Charge Carrier Mobility of Siliconized Liquid Triarylamine Organic Semiconductors by Time-of-Flight Spectroscopy.

2015

View full text Add to dashboard Cite

Triarylamines are a well-established family of organic semiconductors. Recently, we have attached short silicone chains to these molecules to alter their mechanical properties. The resulting compounds are liquids at room temperature. We have undertaken to confirm the suitability of these molecules for use in thin film flexible devices. One fundamental property of semiconductors is the charge carrier mobility, which provides a quantitative estimate for how rapidly charge percolates through a material. The charge carrier mobility for a series of six recently developed liquid siliconized triarylamines was measured using time-of-flight spectroscopy (TOF). In order to evaluate the effect of glass transition temperature on mobility, TOF was performed for different electric fields at temperatures above and below the glass transition temperature. Mobilities were found to compare favorably to the charge carrier mobilities of conventional nonliquid triarylamines. It was further observed that the mobilities conform to the predictions of the disorder formalism for a disordered solid both above and below the glass transition temperature. This suggests that charge transport is dominated by thermally activated intermolecular hopping rather than by any convective or diffusive mass transport within the liquid phase.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Charge Carrier Mobility of Siliconized Liquid Triarylamine Organic Semiconductors by Time-of-Flight Spectroscopy.

2015

View full text Add to dashboard Cite

show abstract

“…As a matter of fact, most of organic semiconductors absorb the ultraviolet (UV) light range because of their molecular nature, and therefore previous studies measured the carrier mobility by using 337 or 355 nm to be the excitation wavelength. 60 73 74 75 76 77 78 79 80 Some of organic materials, however, especially materials with a wide band gap that having either a low absorption coefficient or an absorption wavelength shorter than the deep UV light, face difficulties in selecting the excitation source and render the inaccuracy in determining the carrier mobility. 60 73 75 76 77 Therefore, a wavelength that is transparent to the wide-bandgap materials while having a high photo-response to the CGL should be a more suitable excitation source.…”

Section: Resultsmentioning

confidence: 99%

Downscaling the Sample Thickness to Sub-Micrometers by Employing Organic Photovoltaic Materials as a Charge-Generation Layer in the Time-of-Flight Measurement

Liu

Lee

et al. 2015

Sci Rep

View full text Add to dashboard Cite

Time-of-flight (TOF) measurements typically require a sample thickness of several micrometers for determining the carrier mobility, thus rendering the applicability inefficient and unreliable because the sample thicknesses are orders of magnitude higher than those in real optoelectronic devices. Here, we use subphthalocyanine (SubPc):C70 as a charge-generation layer (CGL) in the TOF measurement and a commonly hole-transporting layer, N,N’-diphenyl-N,N’-bis(1,1’-biphenyl)-4,4’-diamine (NPB), as a standard material under test. When the NPB thickness is reduced from 2 to 0.3 μm and with a thin 10-nm CGL, the hole transient signal still shows non-dispersive properties under various applied fields, and thus the hole mobility is determined accordingly. Only 1-μm NPB is required for determining the electron mobility by using the proposed CGL. Both the thicknesses are the thinnest value reported to data. In addition, the flexibility of fabrication process of small molecules can deposit the proposed CGL underneath and atop the material under test. Therefore, this technique is applicable to small-molecule and polymeric materials. We also propose a new approach to design the TOF sample using an optical simulation. These results strongly demonstrate that the proposed technique is valuable tool in determining the carrier mobility and may spur additional research in this field.

show abstract

“…We deduce that two possibilities should be considered: first, the carrier transport behaviors within some arylamine-containing materials may not be unipolar, electrons may also transport well in these materials comprised of electron-rich arylamine moieties, e.g., Klenkler et al demonstrated the bipolar transport property of N,N′-diphenyl-N,N′-bis(3-methlyphenyl)-[1,1′-biphenyl]-4,4′-diamine (TPD) with similar mobilities for holes and electrons by the time-of-flight (TOF) method. 28 It still could not be confirmed whether TPA-3FEP has bipolar transport behavior, since we failed in obtaining its hole and electron mobilities using general methods like TOF, organic field-effect transistor (OFET), and space-charge-limited current (SCLC). Second, it is also possible that the combination of phosphonate pendants changes the charge transport property of the electron-rich core units and makes the electron transport well within the whole material.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Alternative Carrier Injection/Extraction Inspired by Electrode Interlayers Based on Peripheral Modification of the Electron-Rich Skeleton

Chen

Zhang

Zhou

et al. 2015

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Peripheral modifications of the electron-rich trifluorene-substituted triphenylamine core have been comparatively studied through the linkage of the different polar pendants with fluorene via saturated sp3 hybrid alkyl chains. The work function of electrode could be effectively tuned by the interlayers with or without peripheral pendants of phosphoric acid and phosphonate groups to give selective hole and electron injection/extraction property. Their applications in various vacuum- and solution-processed organic light-emitting diodes and photovoltaic devices were thoroughly investigated. The current comparative study provides valuable exploration on developing high-performance environmentally friendly solvent-processed electrode interlayer materials.

show abstract

Hole and Electron Transport in Triarylamine-Based Charge-Transport Materials Investigated by the Time-of-Flight Method

Cited by 19 publications

References 15 publications

Charge Carrier Mobility of Siliconized Liquid Triarylamine Organic Semiconductors by Time-of-Flight Spectroscopy.

Charge Carrier Mobility of Siliconized Liquid Triarylamine Organic Semiconductors by Time-of-Flight Spectroscopy.

Downscaling the Sample Thickness to Sub-Micrometers by Employing Organic Photovoltaic Materials as a Charge-Generation Layer in the Time-of-Flight Measurement

Alternative Carrier Injection/Extraction Inspired by Electrode Interlayers Based on Peripheral Modification of the Electron-Rich Skeleton

Contact Info

Product

Resources

About