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Charge carrier mobility in non-equilibrated transport in molecular materials

Kania Sylwester, Kościelniak-Mucha Barbara, Kuliński Janusz, Słoma Piotr, Wojciechowski Krzysztof

Scientific Bulletin. Physics / Lodz University of Technology

2019

Vol. 40

37--46

Non-equilibrated transport of charge carriers in the molecular material depends on the structure and packing of the molecules. Explanation of the measurements of the photocurrent generated with use of UV flash light in organic layer needs to define the quantity of charge carriers mobility. Definition of this quantity in the scope of some defined transport model requires the detailed analysis of generation, recombination and charge transfer between neighbouring molecules. The problem is discuss on the basis of transport properties of two anthracene derivatives.

Opis nierównowagowego transportu nośników ładunku w warunkach fotoprądu wzbudzanego impulsem światła wymaga zdefiniowania ruchliwości nośników ładunku. Definicja tej wielkości w odniesieniu do określonego modelu transportu wymaga wnikliwej analizy procesów generacji, rekombinacji i transferu ładunku pomiędzy sąsiadującymi cząsteczkami. W tej pracy do opisu transportu nośników ładunku w antronie i antrachinonie wykorzystano teorię Marcusa–Husha, która dotyczy transportu hoppingowego. Uzyskano prawie identyczne wartości ruchliwości dziur w obu materiałach, tj. 1,7·10-2 cm2/Vs oraz identyczne wartości ruchliwości elektronów 4,7·10-2 cm2/Vs. Pomimo prostoty rozważań teoretycznych uzyskane wyniki obliczeń dają jakościowo poprawny obraz transportu, zgodny z wynikami doświadczalnymi. Dla obu związków wartości ruchliwości obliczone za pomocą teorii Marcusa-Husha zarówno dla transportu dziur jak i dla transportu elektronów są w zakresie transportu hoppingowego.

(Bi,Pb)-Sr-Ca-Cu-O glass-ceramics - superconductor and granular metal

Gazda M., Kusz B., Murawski L., Stizza S., Natali R.

Optica Applicata

2008

Vol. 38, nr 1

153-161

In the (Bi,Pb)-Sr-Ca-Cu-O system, materials of various electrical and superconducting properties may be produced by a glass-ceramic method. As a result of heat treatment, amorphous material partially crystallizes. It causes an increase in the size and/or the number of conducting grains and a decrease in the width of the insulating barriers between them. The resistivity of the samples containing small, weakly coupled grains in the normal state follows the exponential temperature dependence of resistivity, while in the samples with larger intergrain conductivities the dependence is logarithmic. Still stronger connections between the grains lead to linear or almost linear ?(T). The granular character of the (Bi,Pb)4Sr3Ca3Cu4Ox materials also influences their superconducting properties.

Effect of doping on time-of-flight transient currents in twin crystalline layers: a Monte-Carlo study

Rybicki J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

2000

Vol. 4, No 1

33-48

In the paper we present the results of the Monte Carlo simulations of time-of-flight transient currents in hopping systems containing various, concentrations of transport-active centres placed in an inert matrix, and doped with various concentrations of additional transport-active centres, characterised by a different ionisation potential than the host transport centres. Such hopping centre distribution can be found in molecularly doped organic crystals. The carriers are allowed to jump between localised states of two kinds: the host transport sites of concentration c/sub 0/, and the additional doping sites of concentration c/sub d/. We deal only with the dependence of the carrier mobility on doping level, and on the difference of ionisation potentials between the host and dopant centres, at fixed external field and temperature. The results of simulations performed for various dopings, and various hopping sites distributions in energy, are discussed. The carrier jump statistics is discussed in detail.