Thermoelasticity in organic semiconductors determined with terahertz spectroscopy and quantum quasi-harmonic simulations

2020 ◽  
Vol 8 (31) ◽  
pp. 10917-10925 ◽  
Author(s):  
Peter A. Banks ◽  
Jefferson Maul ◽  
Mark T. Mancini ◽  
Adam C. Whalley ◽  
Alessandro Erba ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Vibrational Spectroscopy ◽  
Flexible Electronics ◽  
Terahertz Spectroscopy ◽  
Thermomechanical Response ◽  
Essential Aspect ◽  
Quasiharmonic Approximation

The thermomechanical response of organic semiconducting solids – an essential aspect to consider for the design of flexible electronics – was determined using terahertz vibrational spectroscopy and quantum quasiharmonic approximation simulations.

scholarly journals Mesomorphic Behavior in Silver(I) N-(4-Pyridyl) Benzamide with Aromatic π–π Stacking Counterions

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1666 ◽  
Author(s):  
Issac Torres ◽  
Mauro Ruiz ◽  
Hung Phan ◽  
Noemi Dominguez ◽  
Jacobo Garcia ◽  
...  
Keyword(s):  
Solid State ◽  
Organic Semiconductors ◽  
Flexible Electronics ◽  
Crystalline Solid ◽  
Naval Research ◽  
Scanning Calorimetry ◽  
New Family ◽  
Π Stacking ◽  
Capable Groups ◽  
New Generation

Organic semiconductor materials composed of π–π stacking aromatic compounds have been under intense investigation for their potential uses in flexible electronics and other advanced technologies. Herein we report a new family of seven π–π stacking compounds of silver(I) bis-N-(4-pyridyl) benzamide with varying counterions, namely [Ag(NPBA)2]X, where NPBA is N-(4-pyridyl) benzamine, X = NO3− (1), ClO4− (2), CF3SO3− (3), PF6− (4), BF4− (5), CH3PhSO3− (6), and PhSO3− (7), which form extended π−π stacking networks in one-dimensional (1D), 2D and 3D directions in the crystalline solid-state via the phenyl moiety, with average inter-ring distances of 3.823 Å. Interestingly, the counterions that contain π–π stacking-capable groups, such as in 6 and 7, can induce the formation of mesomorphic phases at 130 °C in dimethylformamide (DMF), and can generate highly branched networks at the mesoscale. Atomic force microscopy studies showed that 2D interconnected fibers form right after nucleation, and they extend from ~30 nm in diameter grow to reach the micron scale, which suggests that it may be possible to stop the process in order to obtain nanofibers. Differential scanning calorimetry studies showed no remarkable thermal behavior in the complexes in the solid state, which suggests that the mesomorphic phases originate from the mechanisms that occur in the DMF solution at high temperatures. An all-electron level simulation of the band gaps using NRLMOL (Naval Research Laboratory Molecular Research Library) on the crystals gave 3.25 eV for (1), 3.68 eV for (2), 1.48 eV for (3), 5.08 eV for (4), 1.53 eV for (5), and 3.55 eV for (6). Mesomorphic behavior in materials containing π–π stacking aromatic interactions that also exhibit low-band gap properties may pave the way to a new generation of highly branched organic semiconductors.

scholarly journals Thermoelasticity in Organic Semiconductors Determined with Terahertz Spectroscopy and Quantum Quasi-Harmonic Simulations

2020 ◽  
Author(s):  
Peter A. Banks ◽  
Jefferson Maul ◽  
Mark T. Mancini ◽  
Adam C. Whalley ◽  
Alessandro Erba ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Density Functional ◽  
Mechanical Response ◽  
Terahertz Spectroscopy ◽  
Harmonic Approximation ◽  
Low Frequency ◽  
Intermolecular Forces ◽  
State Density ◽  
Experimental Apparatus ◽  
Thermoelastic Response

The thermomechanical response of organic semiconducting solids is an essential aspect to consider in the design of materials for advanced applications, and in particular, flexible electronics. The non-covalent intermolecular forces that exist in organic solids not only result in a diverse set of mechanical properties, but also a critical dependence of those same properties on temperature. However, studying the thermoelastic response of solids is experimentally challenging, often requiring large single-crystals and sensitive experimental apparatus. An alternative contactless approach involves using low-frequency vibrational spectroscopy to characterize the underlying intermolecular forces, and then combining this information with solid-state density functional theory simulations to retrieve the mechanical response of materials. This methodology leverages recent advances in the quasi-harmonic approximation to predict the temperature evolution of crystalline structures, dynamics, and associated forces, and then utilizes this information to determine the elastic tensor as a function of temperature. Here, this methodology is illustrated for two prototypical organic semiconducting crystals, rubrene and BTBT, and suggests a new alternative means to characterizing the thermoelastic response of organic materials.

scholarly journals Terahertz short-range mobilities in neat and intermixed regions of polymer:fullerene blends with controlled phase morphology

2018 ◽  
Vol 6 (44) ◽  
pp. 22301-22309 ◽  
Author(s):  
Philipp Krauspe ◽  
Demetra Tsokkou ◽  
Martina Causa' ◽  
Ester Buchaca-Domingo ◽  
Zhuping Fei ◽  
...  
Keyword(s):  
Solar Cell ◽  
Organic Semiconductors ◽  
Short Range ◽  
Terahertz Spectroscopy ◽  
Phase Morphology ◽  
Cell Performance ◽  
Solar Cell Performance

Terahertz spectroscopy unravels the inner working principles of polymer:fullerene blend organic semiconductors with regard to their solar cell performance.

Vibrational Spectroscopy Analysis of Oligothiophene Blend Film

2021 ◽  
Vol 317 ◽  
pp. 457-462
Author(s):  
Siti Zulaikha Ngah Demon ◽  
Nursaadah Ahmad Poad
Keyword(s):  
Thin Film ◽  
Vibrational Spectroscopy ◽  
Flexible Electronics ◽  
Indium Tin Oxide ◽  
Infrared Absorption Spectrum ◽  
Ambient Atmosphere ◽  
Raman Analysis ◽  
Blend Film ◽  
Molecular Ordering ◽  
Crucial Information

One of the challenges in fabricating organic semiconductor thin film is to produce bettermolecular ordering that compromise its electronic properties. Molecular ordering of amorphous thin film can be improved in many ways. Here, high molecular weight polylactic acid (PLA) is introduced as binding matrix to promote 3'''-didodecyl-2,2':5',2'':5'',2'''-quaterthiophene (4T) film’s homogeinity across indium tin oxide (ITO) surface. Molecular ordering of the spin coated biodegradable PLA and 4T blend film processed at ambient atmosphere was studied using two vibrational spectroscopy methods. The complementary analysis of infrared absorption spectrum and Raman spectrum had identified several vibrational modes contributed by thiophene rings and alkyl functional groups. The Raman analysis implied there is a slight change of thiophene ringsʼ molecular orientation due to compressive stress after introduction of polymer. Microscopic characteristics of oligothiophenes especially at the π-π conjugated backbones contained crucial information in order to exploit the oligothiophene as flexible electronics devices.

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