scholarly journals Conduction of Electric Current to Organic Molecules observed by Carrier Transport Mobility Measurements

2021 ◽  
Author(s):  
Toshiki Komatsu
Keyword(s):  
Melting Point ◽  
Electric Current ◽  
Organic Semiconductors ◽  
Carrier Transport ◽  
Organic Materials ◽  
Indirect Evidence ◽  
Transparent Electrode ◽  
Electrical Measurements ◽  
Electrode Cell ◽  
Vertical Field Effect

Organic semiconductors have been studied for many years, but electric current conduction through organic materials has proven difficult in practice. To evaluate the carrier mobility of newly synthesized modified polyacenes, we prepared suitable techniques for determining the physical properties of the polyacenes from electrical measurements. In a transparent electrode cell based on a low-melting-point material, we observed the dark-current dependence on the cooling rate and evaluated the sample impurity. We then developed a vertical field-effect transistor (FET) device for high- melting-point materials that easily measures the transconductance of a single drop of a sample solution. The vertical FET device provides indirect evidence of Marcus’ theory of electric conduction phenomena in aggregated organic materials.

Revealing the mechanism of carrier transport in host-guest systems of organic materials with a modified Poisson and drift-diffusion solver

2020 ◽  
Vol 4 (12) ◽  
Author(s):  
Jun-Yu Huang ◽  
Jiun-Haw Lee ◽  
Yuh-Renn Wu ◽  
Tse-Ying Chen ◽  
Yu-Cheng Chiu ◽  
...  
Keyword(s):  
Carrier Transport ◽  
Organic Materials ◽  
Drift Diffusion

scholarly journals A high-spin ground-state donor-acceptor conjugated polymer

2019 ◽  
Vol 5 (5) ◽  
pp. eaav2336 ◽  
Author(s):  
A. E. London ◽  
H. Chen ◽  
M. A. Sabuj ◽  
J. Tropp ◽  
M. Saghayezhian ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
High Spin ◽  
Ground State ◽  
Conjugated Polymer ◽  
Organic Materials ◽  
Energy Gap ◽  
Light Element ◽  
Paramagnetic Resonance ◽  
Practical Applications ◽  
Polymer Semiconductor

Interest in high-spin organic materials is driven by opportunities to enable far-reaching fundamental science and develop technologies that integrate light element spin, magnetic, and quantum functionalities. Although extensively studied, the intrinsic instability of these materials complicates synthesis and precludes an understanding of how fundamental properties associated with the nature of the chemical bond and electron pairing in organic materials systems manifest in practical applications. Here, we demonstrate a conjugated polymer semiconductor, based on alternating cyclopentadithiophene and thiadiazoloquinoxaline units, that is a ground-state triplet in its neutral form. Electron paramagnetic resonance and magnetic susceptibility measurements are consistent with a high-to-low spin energy gap of 9.30 × 10−3 kcal mol−1. The strongly correlated electronic structure, very narrow bandgap, intramolecular ferromagnetic coupling, high electrical conductivity, solution processability, and robust stability open access to a broad variety of technologically relevant applications once thought of as beyond the current scope of organic semiconductors.

scholarly journals Analytic Solutions for Diffusion on Path Graphs and Its Application to the Modeling of the Evolution of Electrically Indiscernible Conformational States of Lysenin

2020 ◽  
Author(s):  
K. Summer Ware
Keyword(s):  
Conformational Changes ◽  
Lipid Membrane ◽  
Past History ◽  
Current Model ◽  
Indirect Evidence ◽  
Ionic Currents ◽  
Conformational State ◽  
Coelomic Fluid ◽  
Electrical Measurements ◽  
Path Graph

Memory is traditionally thought of as a biological function of the brain. In recent years, however, researchers have found that some stimuli-responsive molecules exhibit memory-like behavior manifested as history-dependent hysteresis in response to external excitations. One example is lysenin, a pore-forming toxin found naturally in the coelomic fluid of the common earthworm Eisenia fetida. When reconstituted into a bilayer lipid membrane, this unassuming toxin undergoes conformational changes in response to applied voltages. However, lysenin is able to "remember" past history by adjusting its conformational state based not only on the amplitude of the stimulus but also on its previous its conformational state. The current model is a simple two-state Markov description which may not describe a system with memory. In this respect, this thesis aims to provide a more accurate description of this toxin's memory and response to external stimuli by applying a more rigorous mathematical approach. The traditional setting for investigating the conformational changes of voltage-responsive channel proteins is based on analyzing the ionic currents recorded through one or many channels in response to applied voltage stimuli. However, this approach provides only indirect evidence of the conformational state of the channel, i.e open (conducting) or closed (non-conducting). Although very useful, this setting is seriously limited by the inability of electrical measurements to discern between electrically identical yet conformational different open or closed states. The literature that inspired this thesis topic consider models of diffusion on a path-graph with one open state and an arbitrary number of closed states. The mathematics typically begins with approximations from a continuous model. In this thesis we study the analytic solution of the system of linear homogeneous differential equations which are probability vectors describing the diffusion process; this involves exponential theory of weighted Laplacian graphs. Since the Laplacian matrix of the path graph is well studied, we have access to both eigenvectors and eigenvalues in terms of roots of unity making for a succinct solution. We find that polynomial weights model the hysteresis successfully.

Organic and nano-structured composite photovoltaics: An overview

2005 ◽  
Vol 20 (12) ◽  
pp. 3167-3179 ◽  
Author(s):  
Sophie E. Gledhill ◽  
Brian Scott ◽  
Brian A. Gregg
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Organic Semiconductors ◽  
Organic Solar Cells ◽  
Organic Materials ◽  
Low Cost ◽  
Open Circuit ◽  
Charge Generation ◽  
Dye Sensitized ◽  
Excitonic Solar Cells

Organic photovoltaic devices are poised to fill the low-cost, low power niche in the solar cell market. Recently measured efficiencies of solid-state organic cells are nudging 5% while Grätzel’s more established dye-sensitized solar cell technology is more than double this. A fundamental understanding of the excitonic nature of organic materials is an essential backbone for device engineering. Bound electron-hole pairs, “excitons,” are formed in organic semiconductors on photo-absorption. In the organic solar cell, the exciton must diffuse to the donor–accepter interface for simultaneous charge generation and separation. This interface is critical as the concentration of charge carriers is high and recombination here is higher than in the bulk. Nanostructured engineering of the interface has been utilized to maximize organic materials properties, namely to compensate the poor exciton diffusion lengths and lower mobilities. Excitonic solar cells have different limitations on their open-circuit photo-voltages due to these high interfacial charge carrier concentrations, and their behavior cannot be interpreted as if they were conventional solar cells. This article briefly reviews some of the differences between excitonic organic solar cells and conventional inorganic solar cells and highlights some of the technical strategies used in this rapidly progressing field, whose ultimate aim is for organic solar cells to be a commercial reality.

Recent progress in pyrazinoacenes containing nonbenzenoid rings: synthesis, properties and applications

2022 ◽  
Author(s):  
Fangyuan Kang ◽  
Jie Yang ◽  
Qichun Zhang
Keyword(s):  
Organic Semiconductors ◽  
Recent Progress ◽  
Organic Materials ◽  
Important Class ◽  
Great Progress ◽  
Synthesis Properties

Azaacenes have emerged as a new and important class of organic materials, and their synthetic strategies and applications as organic semiconductors have gained great progress in recent years. Generally, adopting...

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