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14 introductiondensed phases [63, 70, 71] but requires an high computationalcost and a very large number of fitting parameters.In the present work, we focus on a planar ideally perfectmetal oxide surface (ZnO), so that the role of defectsand its evolution is not critical. Furthermore, at room temperaturemost of the microstructure evolution is expectedin the softer organic part of the system. For these reasonswe adopt the simple combination of Buckingham plus longrange Coulombic interatomic potentials, that represents acompromise between computational cost and accuracy, thereliability of this description being confirmed by severalworks [72, 73].As for the electronic properties of PV interfaces, the DFTapproach provides very good choice but its heavier computationalcost limits the analysis to small portions of theMPMD generated system. The DFT method require somecare in the choice of exchange-correlation functional used.In particular, both the LDA [74] and the GGA [75] functionalssuffer from the problem of the underestimation ofthe band gap for the semiconductors (including the ZnO)[76]. This problem can be partially overcome by using theLDA+U approach [77, 78] or hybrid funcionals (such as theB3LYP [79, 80]). This latter, however, severely increases thecomputational cost.1.4 aims and outline of this thesisThe aim of this thesis work is to generate realistic atomisticmodel for hybrid interfaces and supply informationsfor their design and optimization.In particular, a major emphasis will be given to the morphologicalaspects of the investigated systems, while theelectronic properties will be addressed mainly as a reviewcontribution framed in a more general discussion.The understanding of the hybrid interface requires firstof all the study of the polymer alone, its structure andmechanisms of aggregation. Therefore, the first chapter ofthis work concerns the P3HT polymer studied as singlemolecule (dimer and oligomer) and aggregated bulk includingcrystalline and nanocrystalline phases. Its crystallineproperties and self assembling mechanism are investigated,as well as the structure of polymer nanoclusters.