Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
Abstract
Optical and photovoltaic properties of polyphenylenevinylene derivative –
poly(2-methoxy-5-(3-,7-dimethyl-octyloxy)-1,4-phenylenevinylene (MDMO-PPV) and
its composites with high (40 %) concentration polymethine dyes (PD) – meso-Cl and
hexaindoletricarbocyanine (HITC) films have been studied. Two H-aggregates of dyes
with different energies that weakly depend on the molecular structure of dyes, is formed
in MDMO-PPV with PD in composites films. The efficiency of photogeneration of
charge carrier by these aggregates is greater than the efficiency of photogeneration of
charge carriers by the quasi-isolated molecules of dye. It results in substantial expansion
of the absorption region (in comparison with the absorption region of molecules in
solution) and photosensitivity in the side of higher energies. The presence of PD
aggregates in the films MDMO-PPV influences on their photosensitivity that depends on
PD molecular structure. This dependence can be caused by interaction between the
molecules of MDMO-PPV and dye. In composites MDMO-PPV/HITC, the value of
interaction is low and practically does not influence the efficiency of photogeneration of
charge carriers by MDMO-PPV molecules, which give a considerable contribution to
formation of the photovoltage in 2-3 eV regions. The interaction of meso-Cl and
MDMO-PPV molecules is stronger, and this, probably, results in considerable decrease
of photovoltage in the region of the excitation of MDMO-PPV
