טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentYehoram Bar
SubjectMonte-Carlo Simulation of Transport in Polymers
DepartmentDepartment of Electrical Engineering
Supervisor Full Professor Tessler Nir


Abstract

In the past decade, it has become clear that organic semiconductors are promising materials for many applications, like flexible displays, solar cells and light emitting diodes. The semi conductive behavior of the organic semiconductors or p-conjugated materials is the result of the ‘conjugation’ in the polymer backbone, i.e. the presence of alternating single and double carbon-carbon bonds.


Although we witnessed in the recent years the appearance of new commercial applications that are based on these materials, the basic scientific understanding of the fundamental electro-optical processes in organic semiconductors is far from being complete. As we will show the new mode of transport that deviates from the "normal" Markovian transport - namely, anomalous or dispersive transport plays an important role.


In this research we performed Monte Carlo (MC) simulations and examined charge transport properties in conjugated polymers. The main goal of this research is to examine the transport properties dependence on the charge concentration, namely the non-linearity of charge transport properties. We do not suggest or test new physical models but rather test well established models under special conditions which are better fit to operating devices. Along our simulations two different models were used: the first is Anderson which is more known as Miller-Abrahams, while the second one is the polaronic model which is known as Mott's model. Within those models we tried to explain low concentration and high concentration transport properties, the current profile, the mobility and Einstein Relation (ER) (Diffusion coefficient to mobility ratio) which are dependent on charge concentration.