Charge Transport Properties in Disordered Organic Semiconductors Monte Carlo Simulation
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Date
2021-06-03
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Addis Ababa University
Abstract
In this thesis, we have used a Monte Carlo simulation technique to study the charge carrier
mobility as a function of charge carrier density and electric _eld in disordered organic
semiconducting materials using the lattice model. Our simulations reveal that the charge
carrier mobility versus charge carrier density at lower charge carrier density and disorder
is constant. In contrast, at higher disordered and lower charge carrier density, the charge
carrier mobility increases with charge carrier density. Therefore, the e_ect of the disorder
parameter (^_ = _
kBT ) on the charge carrier mobility is more pronounced than the charge
carrier density at lower charge carrier density. We studied a charge carrier mobility as a
function of the electric _eld for the case of the regular grid and spatial disorder lattice
site with di_erent lattice site spacing parameter r and the ratio of localization length to
the lattice parameter (i. e, _=b). We show that a charge carrier mobility increases with
an electric _eld for the case of the regular grid and spatial disorder lattice site of lower or
equal values of lattice site spacing r to the ratio of _=b. But, at a higher value of lattice
site spacing r to the ratio of _=b, the electric _eld dependence of charge carrier mobility
for spatial disordered lattice sites di_ers from that of the regular grid case. We observed
that both a localization length and lattice parameter are relevant for the electric _eld
variation of charge carrier mobility in both the regular grid and spatial disordered lattice
sites at lower or equal values of lattice site spacing r to the ratio of _=b cases. However, at
higher values of the lattice site spacing r relative to the ratio of _=b, the only parameter
responsible for the electric _eld dependence of charge carrier mobility is the localization
length of disordered organic semiconducting materials.
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Keywords
Charge Transport, Properties, Disordered Organic, Semiconductors, Monte Carlo Simulation