Electronic structure of some organic, inorganic and hybrid materials

This thesis studies the intrinsic properties of organic, inorganic and hybrid materials that are potentially interesting for practical applications in organic electronics and spintronics. Most of the work in this thesis is based on the density functional theory (DFT) implemented in Vienna Ab initio Simulation Package (VASP). It showed great success both for studying molecules and solids. The essential part of this work is the result of a fruitful collaboration with the experimental studies. In Chapter 2 we studied the intrinsic properties of organic semiconductors in a quest for realizing ambipolar transport (transport for both holes and electrons). Based on our calculations of the electronic band structure, we established the conditions for the ambipolar transport for specific type of materials - acene-TCNQ compounds. These organic crystals have a very similar layered crystal structure but a very different electronic band structure of the valence and the conduction bands which has immediate consequence on the ambipolar transport. We focused on the newly synthesized crystals of the charge-transfer salt tetracene-TCNQ and similar to it the perylene-TCNQ, potentially interesting for realization of ambipolar transport. The band structures were calculated from first principles using DFT. The hole and the electron transport properties are predicted to be equally good in perylene-TCNQ, in contrast to the tetracene-TCNQ, which has good transport properties for electrons only.