**5. Conclusions**

In this chapter we summarize some of the most important results of our work in the field of new materials for applications in the field of optoelectronics. Our interest was focused on organic molecules containing electrons, occupying non-localised molecular orbitals in strongly conjugated systems, such as aromatic derivatives compounds (benzil, m-DNB, PTCDA, ZnPc, Alq3, TPyP) for which we have evidenced large transparency domain and good fluorescence emission.

We have realised a comparative investigation on the properties of the same aromatic deriva‐ tive compound as bulk and thin film material showing both good optical, including lumi‐ nescent, properties. The interest in studying bulk organic crystals is justified by the perspective to use these materials as a crystalline host matrix both for organic and inorganic guests/inclusions. The organic matrix assures an efficient fluorescence mechanism and from the guest component it is expected an improvement in stability, emission properties of the matrix and electrical mobility. A special attention was paid to the preparation methods both for bulk crystals (emphasising the correlation between the growth interface stability and quality of the organic crystal) and thin films (emphasising the effect of the thin film deposi‐ tion method -directional solidification, vacuum evaporation, MAPLE- on the properties of the organic film and heterostructures).

Thin films from the above mentioned aromatic derivatives are preferred as organic matrix for host/guest systems because of the major problems associated with bulk crystalline matri‐ ces determined by the difficulties of their growing, processing and doping to assure homo‐ geneous distribution of the guest atoms.

Important results have been bought in the field of molecular organic matrix based on aro‐ matic derivatives (benzil, m-DNB)/inorganic (iodine, silver, sodium) or/and organic (m-DNB, naphthalene, bulk) composite systems and in the field of composite films prepared from polymeric matrix and active monomeric inclusions based on π-conjugated systems containing functional groups with special properties, to improve the properties of film form‐ ing, emission properties of the matrix and the charge carrier mobility in the matrix, with the purpose to obtain materials for potential optoelectronic applications.

We have emphasised the effect of the polycarbonate of bisphenol A matrix on the properties of the synthesised amidic monomers with –CN and –NO2 substituent groups with the pur‐ pose to modify the local molecular environment of the monomer and change the optical and electrical properties of the films.
