Anomalous Temperature Dependence of Solvent-Enhanced Dye Diffusion In Polymer Films

2002 ◽  
Vol 725 ◽  
Author(s):  
T. Graves-Abe ◽  
F. Pschenitzka ◽  
J.C. Sturm
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependence ◽  
Polymer Film ◽  
Light Emitting Diode ◽  
Solvent Vapor ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Thermally Driven

AbstractOne promising method to pattern full color polymer Organic Light-Emitting Diode (OLED) displays is to print dye from a pre-patterned organic film onto a spin-cast polymer and then diffuse the dye into the film at room temperature in a solvent vapor environment. This method utilizes the well-known tendency for a polymer film to absorb solvent vapor, which depresses the glass transition temperature of the polymer and dramatically increases diffusion the dye. In this work, we have studied the temperature dependence of this process. The dye coumarin 6 (C6) was transferred onto films consisting of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)- 1,3,4-oxadiazole (PBD) mixed with the polymer poly(9-vinylcarbazole) (PVK). Samples were then placed on a heated stage in a chamber and exposed to acetone vapor to diffuse the C6 into the polymer film. The profile of the diffused dye was determined by depthdependent photoluminescence measurements and Secondary Ion Mass Spectroscopy. We observed that the amount of diffused dye decreased at higher temperatures, in contrast to conventional thermally-driven diffusion. The results are understood by noting that the decrease in the polymer glass-transition temperature and the corresponding rapid increase in dye diffusivity depend on the quantity of solvent absorbed by the polymer, which decreases as the temperature of the polymer is raised.

Solvent-enhanced Dye Diffusion in Polymer This-Films for OLED Application

2001 ◽  
Vol 665 ◽  
Author(s):  
F. Pschenitzka ◽  
K. Long ◽  
J. C. Sturm
Keyword(s):  
Polymer Film ◽  
Light Emitting Diode ◽  
Nile Red ◽  
Dye Transfer ◽  
Solvent Vapor ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Solvent Absorption ◽  
Dye Diffusion ◽  
Materials Used

ABSTRACTA method of solvent-enhanced dye diffusion in polymer films for organic light-emitting diode (OLED) application is introduced. After an initial dye transfer from a dye source substrate into the top of the electractive polymer film, the device substrate is then exposed to solvent vapor. Due to solvent absorption by the polymer film, the glass transition temperature of the polymer is significantly decreased, which leads to greatly enhanced diffusion of the dye in the polymer film. Secondary ion mass spectroscopy shows that the temperature for dye diffusion can be decreased by 150 °C. OLEDs with 0.4% external quantum efficiency were demonstrated. The materials used are the polymer poly(9-vinylcarbazole) (PVK) combined with electron transport molecules (PBD), and the dyes coumarin 47, coumarin 6 and Nile red.

Poly(Binaphthalenevinylene-alt-Phenylenevinylene) Derivatives: Novel Luminescent Polymers for Light-Emitting Devices

1999 ◽  
Vol 598 ◽  
Author(s):  
Lixin Zheng ◽  
Xuezhong Jiang ◽  
Michelle S. Liu ◽  
Alex K-Y. Jen
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Model Compound ◽  
Condensation Reaction ◽  
Spectral Characteristics ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Luminescent Polymers

ABSTRACTNovel conjugated light-emitting polymers were synthesized via a Wittig-Horner condensation reaction between a binaphthyl dicarbaldehyde and a series of electron-rich or electron-deficient aryl diphosphonates. After comparing these materials with the model compound, 4c, it was revealed that the introduction of a twisted, non-coplanar binaphthyl structure provided an effective approach for tailoring the spectral characteristics of the polymers and improving their solubility and thermal stability (glass transition temperature, Tg, 200°C). Furthermore, the band structures of the polymers could be fine-tuned by changing the electronic properties of the bridging aromatic units. The electroluninescence (EL) and device characteristics were also reported in this paper.

Blue phosphorescent organic light-emitting devices based on carbazole/thioxanthene-S,S-dioxide with a high glass transition temperature

2015 ◽  
Vol 3 (24) ◽  
pp. 6192-6199 ◽  
Author(s):  
Young Pyo Jeon ◽  
Kyu Sung Kim ◽  
Kyeong Kyun Lee ◽  
In Kyu Moon ◽  
Dong Chul Choo ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Host Material ◽  
High Glass Transition Temperature ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Organic Light Emitting Devices ◽  
Blue Phosphorescent

A bipolar host material for blue organic light-emitting devices was synthesized by incorporating electron-donating carbazole and electron-accepting thioxanthene-S,S-dioxide into one molecule using a solventless green reaction.

A Model for Irradiation-Induced Amorphization

1997 ◽  
Vol 504 ◽  
Author(s):  
S. X. Wang ◽  
L. M. Wang ◽  
R. C. Ewing
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependence ◽  
Dose Rate ◽  
Volume Fraction ◽  
Ion Irradiation ◽  
Crystallization Rate ◽  
Single Equation ◽  
Sigmoidal Functions

ABSTRACTA model based on cascade melting and recrystallization is derived to describe ion irradiation-induced amorphization. The accumulation of amorphous volume fraction during irradiation is represented in a single equation. Depending on the extent of recrystallization of a subcascade, the amorphous volume accumulation can be described by a set of curves that change from exponential to sigmoidal functions. The parameters (including temperature, cascade size, crystallization rate, glass transition temperature, dose rate) that affect the extent of recrystallization are included in the model. The model also describes the temperature dependence of critical dose for amorphization.

scholarly journals Glass transition temperature prediction of disordered molecular solids

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Kun-Han Lin ◽  
Leanne Paterson ◽  
Falk May ◽  
Denis Andrienko
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Organic Semiconductors ◽  
Absolute Error ◽  
Organic Light Emitting Diodes ◽  
Molecular Solids ◽  
Reliable Prediction ◽  
Light Emitting ◽  
Molecular Ordering

AbstractGlass transition temperature, Tg, is the key quantity for assessing morphological stability and molecular ordering of films of organic semiconductors. A reliable prediction of Tg from the chemical structure is, however, challenging, as it is sensitive to both molecular interactions and analysis of the heating or cooling process. By combining a fitting protocol with an automated workflow for forcefield parameterization, we predict Tg with a mean absolute error of ~20 °C for a set of organic compounds with Tg in the 50–230 °C range. Our study establishes a reliable and automated prescreening procedure for the design of amorphous organic semiconductors, essential for the optimization and development of organic light-emitting diodes.

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