In this work, one-dimensional (1D) nanomaterials were created from an organic semiconductor material via vapor deposition on flexible polyethylene terephthalate (PET) substrates. Tri-(8-hydrooxyquioniline) aluminum (Alq(3)) molecules readily assembled into nanotubes under ambient pressure. Vertically grown Alq(3) nanotube arrays on PET substrates emitted green photoluminescent light after excitation at 380nm. This extremely simple approach offers a straightforward pathway for creating and directing vertical arrays of organic semiconducting building blocks through molecular assembly, and can be used to assemble high-performance optoelectronic devices.