Аннотация:The using of polymeric materials as the basis of photovoltaic cells provides high
manufacturability and low cost of production of flexible polymer solar cells (PSC) of a large
area. The recent increase in a parameter of the solar energy conversion efficiency (up to 10 %)
for materials based on conjugated polymers and fullerenes makes commercialization of
plastic solar cell gainful. The peculiarity of the manufacture of PSC leads to the fact that the
photoactive layer of photovoltaic cells is formed as a thermodynamically unstable system
(with a kinetically frozen state). As a result of constant heating/cooling cycles, a gradual
phase separation of the initial components occurs. Thus, searching for key factors helping to
increase the long-term stability of organic solar cells is the main challenge for their
widespread adoption in everyday practice.
Because of the lack of fundamental understanding of the phase behavior of donoracceptor
mixtures in the active layers of organic photovoltaic cells, we are carrying out a
systematic study of the structural changes that occur after the phase separation of different
systems based on a mixture of conjugated polymers with fullerenes. In the report, we discuss
our first results on computer simulations of polymer nanocomposites based on conjugated
polymers and fullerenes. Specifically, we are interested in the effect of the chemical structure
of donor-acceptor copolymers on the morphology of nanocomposites and their thermal
stability. Representative systems, that we have chosen to study, are polythiophenes such as
poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(3-2-methylbutylthiophene) (P3MBT), poly(3-
2-metilpentilthiophene) (P3MPT), and fullerene [6,6]-phenyl C61 butyric acid methyl ester
(PC61BM).
We have constructed and parameterized a coarse-grained model of a photoactive layer
based on selected polymers and PC61BM. This model is used to study the structure of the
photoactive layer. In addition, within the framework of the atomic molecular dynamics
method, we carried out a study of the miscibility of selected conjugated polymers with
PC61BM. The obtained results make it possible to predict the relationship of the chemical
structure of conjugated polymer chains to the morphology of conjugated polymers/fullerenes
nanocomposites, their thermophysical properties, the stability of the interface, and to perform
the comparison of these data with the optoelectronic properties and functioning of the
photocells. The forthcoming experimental studies will allow us to calibrate the design of PSC
better.
The research is carried out using the equipment of the shared research facilities of
HPC computing resources at Lomonosov Moscow State University and the resources of the
federal collective usage center Complex for Simulation and Data Processing for Megascience
Facilities at NRC “Kurchatov Institute” (ministry subvention under agreement
RFMEFI62117X0016), http://ckp.nrcki.ru/. The financial support of the Russian Foundation
for Basic Research (project № 19-53-52004) and the Ministry of Science and Technology of
Taiwan (Project MOST 108-2923-E-002-001-MY3) are highly appreciated.