[institut] SCL seminar (povodom izbora u zvanje), Marko Mladenovic, petak 6. septembar u 14:00

[Nenad Vukmirović]

Поштоване колегинице и колеге,

Позивам вас на СЦЛ семинар који ће у петак 6. септембра 2013. године у
14:00 у читаоници Института за физику одржати Марко Младеновић (СЦЛ, 
Институт за физику у Београду) поводом предстојећег избора у звање 
истраживач сарадник. Наслов семинара је:

Electronic States at Low-Angle Grain Boundaries in Polycrystalline 
Naphthalene

Abstract:

Organic semiconductors are materials of great promise for electronic 
devices, such as organic field-effect transistors (FETs), organic 
light-emitting diodes (LEDs), and organic solar cells (OSCs). Their 
advantage over inorganic counterparts is that they are flexible and have 
a low processing cost. However, devices made of organic semiconductors 
still have relatively low charge mobility and low efficiency. Thin films 
of crystalline organic semiconductors have a polycrystalline form, which 
is composed of many different crystalline grains.  Previous works 
indicate that grain boundaries are the most limiting intrinsic factor 
for efficient charge transport in small molecule based polycrystalline 
organic semiconductors.

We have investigated the influence of grain boundaries on electronic 
properties of polycrystalline organic semiconductor naphthalene. Atomic 
structure of grain boundaries was found using a Monte Carlo method, 
while electronic structure calculations were performed using the density 
functional theory based charge patching method. We found that grain 
boundaries introduce trap states within the band gap of the material. 
Wave functions of these states are localized on closely spaced pairs of 
molecules from opposite sides of the boundary. The energies of trap 
states are strongly correlated with the distances between the molecules 
in the pair. These findings were used to calculate the electronic 
density of trap states, which was found to exhibit a qualitatively 
different behavior for grain boundaries perpendicular to the a and b 
direction of the naphthalene unit cell [1].

[1] M. Mladenovic, N. Vukmirovic and I. E. Stankovic, J. Phys. Chem. C 
117, 15741 (2013).

Срдачан поздрав,

-- 
Др Ненад Вукмировић,
Виши научни сарадник,
Лабораторија за примену рачунара у науци,
Институт за физику Београд,
Србија.
URL: http://www.scl.rs/nenad