In
recent years, monolayer organic field-effect devices such as transistors
and sensors have demonstrated their high potential. In contrast, monolayer
electroluminescent organic field-effect devices are still in their
infancy. One of the key challenges here is to create an organic material
that self-organizes in a monolayer and combines efficient charge transport
with luminescence. Herein, we report a novel organosilicon derivative
of oligothiophene–phenylene dimer <b>D2-Und-PTTP-TMS</b> (D2, tetramethyldisiloxane; Und, undecylenic spacer; P, 1,4-phenylene;
T, 2,5-thiophene; TMS, trimethylsilyl) that meets these requirements.
The self-assembled Langmuir monolayers of the dimer were investigated
by steady-state and time-resolved photoluminescence spectroscopy,
atomic force microscopy, X-ray reflectometry, and grazing-incidence
X-ray diffraction, and their semiconducting properties were evaluated
in organic field-effect transistors. We found that the best uniform,
fully covered, highly ordered monolayers were semiconducting. Thus,
the ordered two-dimensional (2D) packing of conjugated organic molecules
in the semiconducting Langmuir monolayer is compatible with its high-yield
luminescence, so that 2D molecular aggregation per se does not preclude
highly luminescent properties. Our findings pave the way to the rational
design of functional materials for monolayer organic light-emitting
transistors and other optoelectronic devices