TOWARDS A BETTER UNDERSTANDING OF POLYMER-BASED LIGHT-EMITTING-DIODES- A THEORETICAL INSIGHT INTO THE BASIC PHENOMENA

In this contribution, we try to illustrate that quantum-chemistry calc ulations can prove useful to comprehend better the phenomena occurring in the active layer of polymer-based light-emitting diodes. We review the results of recent theoretical calculations conducted at the corre lated level on conjugated oligomers that address several topics of pri me interest in the search of new routes towards the achievement of dev ices with enhanced characteristics. These studies performed on oligome rs representative of poly(para-phenylenevinylene) and polythiophene de al with: (i) the modeling of the optical properties of the conjugated polymers involved in the emitting layer; (ii) the investigation of the relative locations of, and relaxation phenomena taking place in, the lowest singlet and triplet excited states; and (iii) the analysis of t he effects of derivatization of the conjugated backbone. The theoretic al approach we follow allows us to rationalize a wide range of experim ental measurements and to provide guidelines in the design of novel at tractive materials.