Molecular modelling in designing electronically conducting polymers * Kamila OLECH, Jadwiga SOLODUCHO † , Szczepan ROSZAK ‡ Keywords: organic semiconductors; computational studies; electronic devices Abstract: Conjugated organic systems attract research interest due to their broad application in optical and electronic devices. Herein we present an overview of computational methods use- ful in designing novel donor-acceptor polymers. Computational studies have been recently applied in designing new organic semi- conducting polymers of xanthene. Based on the results of DFT (density functional theory) and TDDFT (time-dependent func- tional theory) calculations a group of promising precursors of conducting polymers was designed and selected to further syn- thetic investigations. Influence of the presence and position of heteroatoms on electronic properties of corresponding polymers was examined. Some general trends observed during the study are briefly summarized below. The calculations focus on HOMO and LUMO energy, singlet/triplet excitation energy, band gap values and ionization potentials. The correlation of theoretical results with values measured electrochemically and in a spectro- scopic approach is discussed. 1. Introduction Conjugated polymers are novel materials that possess not only the optoelectronic properties of semiconductors but also the mechanical properties and the process- ing advantages of polymers (Chujo, 2010). They have many applications they may be used as: light-emitting materials, photovoltaic materials, thin film transistors, chemo/biosensors, biofuel cells, and so on (Skotheim et al., 1998). Significant experi- mental and computational efforts have been made to study the electronic properties of conjugated polymers. These investigations are limited by poor solubility of polymers * Kamila Olech is co-financed by the European Union as part of the European Social Fund. Jadwiga Soloducho and Szczepan Roszak thank Wroclaw University of Technology and NCN Grant No. 2012/05/B/ST5/00749.The Wroclaw Centre of Computing and Networking is acknowledged for generous allotments of computer time. † Department of Medicinal Chemistry and Microbiology, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland ‡ Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland