Hopping charge transport in organic materials

Abstract

General properties of the transport of charge carriers (electrons and holes) in disordered organic materials are discussed. It was demonstrated that the dominant part of the total energetic disorder in organic material is usually provided by the electrostatic disorder, generated by randomly located and oriented dipoles and quadrupoles. For this reason this disorder is strongly spatially correlated. Spatial correlation directly governs the field dependence of the carrier drift mobility. Shape of the current transients, which is of primary importance for a correct determination of the carrier mobility, is considered. A notable feature of the electrostatic disorder is its modification in the vicinity of the electrode, and this modification takes place without modification of the structure of the material. It is shown how this phenomenon affects characteristics of the charge injection. We consider also effect of inter-charge interaction on charge transport.

Electrochemical Effects in Thermoelectric Polymers

“…Methods to control the electrical conductivity in conjugated polymers are well-known, but strategies to maximize the Seebeck coefficient without compromising electrical conductivity are of great interest, because the Seebeck coefficient and electrical conductivity are normally inversely coupled . Improvements to the Seebeck coefficient of inorganic materials are typically achieved through band structure engineering and nanostructuring, − but this strategy is more complex in conjugated polymers due to differences in charge transport mechanism and structural disorder. − Polymers based on ethylenedioxythiophene, known as PEDOT, have been shown to have the highest thermoelectric performance. ,,− PEDOT:PSS is a phase separated blend of an electrically conductive conjugated polymer PEDOT and the ion conducting polymer polystyrenesulfonic acid (H-PSS). H-PSS is hygroscopic leading to efficient ion conduction at room temperature under high relative humidity conditions due to water uptake. − The movement of ions under a temperature gradient in the mixed conductor PEDOT:PSS has been shown to result in a high ionic contribution to the overall Seebeck coefficient in addition to the electronic component at the initial application of the thermal gradient, as shown by Wang et al However, the ionic Seebeck effect is transient and decays rapidly with time, enhancing the thermoelectric power factor for approximately 100 s .…”

Microscopic theory of organic magnetoresistance based on kinetic equations for quantum spin correlations

“…The low-field mobility in organic semiconductors is often extremely small ∼ 10 −8 − 10 −6 cm 2 /V s [35][36][37]. However, these small values can be related to the long-range correlations of electrostatic potential produced by the unscreened molecular dipoles [38][39][40]. There is an evidence that at small length-scales the electron mobility can be much higher [41].…”

Psychological peculiarities of children –refugees from the zone of armed conflict in the southeast of Ukraine

“…1 Stepanova E.I., 1 Bazyka D.A., 2 Polka N.S., 1 Poznysh V.A., 1 Kolpakov I.E., 1 Vdovenko V.Yu. 1 animal» revealed the presence of anxiety, aggressiveness, and exhaustion in the overwhelming majority of them. Based on the prevalence of a high level of symptoms of the symptom complex or their combination, 5 observation groups were formed and typological personality traits of children were determined.…”

“…У світовому співтоваристві спостерігаються також негативні тенденції, пов'язані зі збільшенням кількості переселенців і біженців. , За даними Управління Верховного комісара ООН у справах біженців, у доповіді «Глобальні тенденції» констатується, що серед країн світу на 1 січня 2017 року Україна посідала 8 місце після Сирії, Колумбії, Ірану, Судану, Ємену, Нігерії та Південного Судану за кількістю внутрішньопереміщених осіб [1][2][3][4][5]. Роки тяжких випробувань і для людей, і для країни змінили багато що.…”

“…У Дитячому фонді ООН зауважили, що майже 400 тисяч дітей України потребують гуманітарної допомоги у зв'язку з бойовими діями, що тривають, з постійним погіршенням умов проживання у зоні збройного конфлікту, П ПСИХОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ДЕТЕЙ -ПЕРЕСЕЛЕНЦЕВ ИЗ ЗОНЫ ВООРУЖЕННОГО КОНФЛИКТА НА ЮГО-ВОСТОКЕ УКРАИНЫ 1 Степанова Е.И., 1 Базыка Д.А., 2 Полька Н.С., 1 Позныш В.А., 1 Колпаков И.Е., 1 Вдовенко В.Ю. 1…”