(1)benzothieno(3,2-b)benzothiophene (BTBT) derivatives raised a considerable interest as active, p-dopable molecular materials in the preparation of Organic Field Effect Transistors (OFETs) . The main reasons for their success are the absolute performances - BTBT derivatives possess some of the highest hole mobilites reported in the literature - and a straight-forward synthetic access. Parent unsubstituted BTBT can be readily prepared in one step from inexpensive materials. Also, late stage functionalization is generally possible, thus enabling the preparation of a vast library of compounds directly branching from preformed BTBT. Functionalization with either electron-donating or electron-withdrawing groups aimed at tuning the opto-electronic properties is more seldom reported. In particular, development of n-type semiconductors based on the BTBT structure has not been reported yet. In this regard, we present selected results of a systematic investigation of BTBT derivatives based on a fine comparison between synthesis activities and ab initio simulations. In detail, synthetic targets have been individuated, and their opto-electronic and redox properties have been calculated by using ab initio simulations based on density functional theory . The most promising compounds have been actually synthesized and characterized, and their properties have often suggested further synthetic steps to tailor the features of modified products. Fluorination of side chains and direct oxidation of the BTBT core have both demonstrated potentialities as synthetic routes toward n-type BTBT derivatives . Such potentialities are also supported by ab initio simulations of complex electrodes : gold surfaces, chemically modified by self assembled monolayers of organic thiols and in contact with BTBT derivatives are characterized by structural and electronic interfacial properties compatible with the injection of n-type charge carriers into the active layers of optoelectronic devices.
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