Enhancing exciton diffusion in porphyrin thin films using peripheral carboalkoxy groups to influence molecular assembly

2016 ◽  
Vol 4 (24) ◽  
pp. 5602-5609 ◽  
Author(s):  
Meesha Kaushal ◽  
Angy L. Ortiz ◽  
Jennifer A. Kassel ◽  
Nikolas Hall ◽  
Taesoo D. Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Assembly ◽  
Singlet Exciton ◽  
Exciton Diffusion ◽  
Molecular Arrangement ◽  
Solution Cast ◽  
Diffusion Properties

The effects of molecular arrangement and orientation on the singlet exciton diffusion properties of carboalkoxyphenylporphyrins were investigated in solution-cast thin films.

The effects of heavy atoms on the exciton diffusion properties in photoactive thin films of tetrakis(4-carbomethoxyphenyl)porphyrins

2015 ◽  
Vol 3 (6) ◽  
pp. 1243-1249 ◽  
Author(s):  
Angy L. Ortiz ◽  
Graham S. Collier ◽  
Dawn M. Marin ◽  
Jennifer A. Kassel ◽  
Reynolds J. Ivins ◽  
...  
Keyword(s):  
Thin Films ◽  
Monte Carlo ◽  
Diffusion Coefficient ◽  
Diffusion Length ◽  
Heavy Atoms ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Quenching Efficiency ◽  
Diffusion Properties

The exciton diffusion coefficient (D) and exciton diffusion length (LD) for three tetrakis(4-carbomethoxyphenyl)porphyrins were obtained by fitting the quenching efficiency and PL lifetime to a 3D exciton Monte Carlo ediffusion model.

Morphological transformations in solution-cast Styrene-Butadiene-Styrene (SBS) triblock copolymer thin films

1995 ◽  
Vol 53 ◽  
pp. 184-185
Author(s):  
Ginam Kim ◽  
W. Marsillo ◽  
M. Libera
Keyword(s):  
Thin Films ◽  
Triblock Copolymer ◽  
Annealing Treatment ◽  
Minor Component ◽  
Solvent Evaporation ◽  
Single Crystal Substrate ◽  
Transparent Films ◽  
Crystal Substrate ◽  
Solution Cast ◽  
Morphological Transformations

The fact that block copolymers can assume a range of morphologies depending upon such variables as relative block length and molecular weight is now well known. In the case of poly(styrene)[PS]-poly(butadiene)[PB]-poly(styrene) (SBS) triblock copolymer, the morphologies range from spheres (roughly ~20% minor component), to cylinders (roughly 20%~35% minor component), to lamellae (roughly equal component fractions) Most recently, there has been increasing interest in transformations between morphologies by thermal annealing. This paper describes initial results studying the effect of solvent evaporation rate and post-casting annealing treatment on the morphology of SBS thin films.TEM specimens were prepared by solution casting electron transparent films. 50 μl of 0.1 wt% SBS (30% styrene, Mw=14,000, Scientific Polymer Products, Inc.) dissolved in toluene was deposited on a polished NaCl single crystal substrate placed in a small dish. After solvent evaporation the film was cut into small squares, floated from the salt in water, and each square was collected on a Cu grid.

Determining the C60 molecular arrangement in thin films by means of X-ray diffraction

2011 ◽  
Vol 44 (5) ◽  
pp. 983-990 ◽  
Author(s):  
Chris Elschner ◽  
Alexandr A. Levin ◽  
Lutz Wilde ◽  
Jörg Grenzer ◽  
Christian Schroer ◽  
...  
Keyword(s):  
Thin Films ◽  
Structural Information ◽  
Grazing Incidence ◽  
Test Material ◽  
C60 Fullerene ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Arrangement ◽  
Diffraction Patterns

The electrical and optical properties of molecular thin films are widely used, for instance in organic electronics, and depend strongly on the molecular arrangement of the organic layers. It is shown here how atomic structural information can be obtained from molecular films without further knowledge of the single-crystal structure. C60 fullerene was chosen as a representative test material. A 250 nm C60 film was investigated by grazing-incidence X-ray diffraction and the data compared with a Bragg–Brentano X-ray diffraction measurement of the corresponding C60 powder. The diffraction patterns of both powder and film were used to calculate the pair distribution function (PDF), which allowed an investigation of the short-range order of the structures. With the help of the PDF, a structure model for the C60 molecular arrangement was determined for both C60 powder and thin film. The results agree very well with a classical whole-pattern fitting approach for the C60 diffraction patterns.

scholarly journals Electrical Transport and Grain Growth in Solution-Cast, Chloride-Terminated Cadmium Selenide Nanocrystal Thin Films

ACS Nano ◽  
2014 ◽  
Vol 8 (7) ◽  
pp. 7513-7521 ◽  
Author(s):  
Zachariah M. Norman ◽  
Nicholas C. Anderson ◽  
Jonathan S. Owen
Keyword(s):  
Thin Films ◽  
Cadmium Selenide ◽  
Grain Growth ◽  
Electrical Transport ◽  
Solution Cast

scholarly journals Ultrafast Exciton Dynamics in Two Dimensional Covalent Organic Frameworks Reveals Size Dependence to Exciton Diffusion

2020 ◽  
Author(s):  
Nathan C. Flanders ◽  
Matthew S. Kirschner ◽  
Pyosang Kim ◽  
Thomas Fauvell ◽  
Austin Evans ◽  
...  
Keyword(s):  
High Performance ◽  
Transient Absorption ◽  
Domain Size ◽  
Spectroscopic Techniques ◽  
Two Dimensional ◽  
Exciton Dynamics ◽  
Singlet Exciton ◽  
Exciton Diffusion ◽  
Absorption Studies ◽  
Exciton Annihilation

<p>Large singlet exciton diffusion lengths are a hallmark of high performance in organic based devices such as photovoltaics, chemical sensors, and photodetectors. In this study, exciton dynamics of a two-dimensional covalent organic framework, COF- 5, is investigated using ultrafast spectroscopic techniques. Following photoexcitation, the COF-5 exciton decays via three pathways: 1) excimer formation (4 ± 2 ps), 2) excimer relaxation (160 ± 40 ps), and 3) excimer decay (>3 ns). Excitation fluence-dependent transient absorption studies suggest that COF-5 has a relatively large diffusion coefficient (0.08 cm2/s). Furthermore, exciton-exciton annihilation processes are characterized as a function of COF-5 crystallite domain size in four different samples, which reveal domain- size dependent exciton diffusion kinetics. These results reveal that exciton diffusion in COF-5 is constrained by its crystalline domain size. These insights indicate the outstanding promise of delocalized excitonic processes available in 2D COFs, which motivate their continued design and implementation into optoelectronic devices. </p>

Singlet Exciton Diffusion in Organic Crystals Based on Marcus Transfer Rates

2014 ◽  
Vol 10 (3) ◽  
pp. 1242-1255 ◽  
Author(s):  
Vera Stehr ◽  
Reinhold F. Fink ◽  
Bernd Engels ◽  
Jens Pflaum ◽  
Carsten Deibel
Keyword(s):  
Organic Crystals ◽  
Transfer Rates ◽  
Singlet Exciton ◽  
Exciton Diffusion

The Preparation and Properties of A New Family of Amorphous Fluoropolymers: Teflon® Af

1989 ◽  
Vol 167 ◽  
Author(s):  
Paul R. Resnick
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Thermal Properties ◽  
Physical Properties ◽  
Chemical Resistance ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
New Family ◽  
The Family ◽  
Solution Cast

AbstractTeflon® AF is a family of amorphous fluoropolymers with glass transition temperatures as high as 300° based on bis-2,2-trfluoromethyl-4,5-difluoro-1,3-dioxole, (I), which has unusual properties [1–3] (Figure 1). The family retains the superior electrical, chemical resistance and thermal properties associated with fluoropolymers. In addition the polymers have high optical clarity, limited solubility in some commercially available perfluorinated ethers such as Fluorinert® FC-75 and improved physical properties below their glass transition temperatures (Figure 2). Teflon® AF polymers may be either solution cast into clear micron thin films or melt processed into a variety of forms.

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