  Typical device architectures in polymer-based optoelectronic devices, such as
field effect transistors organic light emitting diodes and photovoltaic cells
include sub-100 nm semiconducting polymer thin-film active layers, whose
microstructure is likely to be subject to finite-size effects. The aim of this
study was to investigate effect of the two-dimensional spatial confinement on
the internal structure of the semiconducting polymer poly(9,9-dioctylfluorene)
(PFO). PFO melts were confined inside the cylindrical nanopores of anodic
aluminium oxide (AAO) templates and crystallized via two crystallization
strategies, namely, in the presence or in the absence of a surface bulk
reservoir located at the template surface. We show that highly textured
semiconducting nanowires with tuneable crystal orientation can be thus
produced. Moreover, our results indicate that employing the appropriate
crystallization conditions extended-chain crystals can be formed in
confinement. The results presented here demonstrate the simple fabrication and
crystal engineering of ordered arrays of PFO nanowires; a system with potential
applications in devices where anisotropic optical properties are required, such
as polarized electroluminescence, waveguiding, optical switching, lasing, etc.
