TOPOS addresses a deeper understanding of growth processes of organic films with the aim to develop nano-scale organic field-effect transistors (i.e. transistors with source-drain inter-electrodes distance varying from hundreds to a few nanometres). Fabrication of nano-scale organic field-effect transistors (OFET) is an attractive and challenging task involving both technological and fundamental issues. Our approach to nano OFET fabrication combines a sophisticated nano-scale fabrication technique, i.e. e-beam lithography, adopted to engineer the device at the nanoscale, with the unique ability of Supersonic Molecular Beam Epitaxy (SuMBE) to control morphology, structure and interfaces of molecular organic layers. Such combination of up to date methods is uniquely suitable to thoroughly study the key factors determining the performance of the nano-transistors and hence for determining strategies towards new generations of devices.Our tasks involve: choice of the semiconductor material, optimisation of the growth of the organic active layer, selection of dielectric and electrode(s) material, substrate processing and patterning. We expect that our project will give a boost to the state-of-the-art of OFETs. Merging of two highly capable techniques (e-beam lithography and SuMBE) will enable the fabrication of well-defined and controlled samples, a critical key to improve our fundamental understanding of device physics at the nano-scale. In particular optimisation of nano-electrodes and tuning of the active layer morphology will make possible the study and the optimisation of device performance as a function of the channel length, including exploration of electrical properties down to the molecular level. This is something that is very much required by the organic electronics community.