PhD Student: Marta Rodríguez López

Directors: Marta González Silveira, UAB Senior Researcher in Thermal Properties of Nanoscale Materials,  Group at ICN2.

Short Abstract: The manipulation of molecular orientation is a well established target in organic electronics and energy-harvesting applications since it may affect relevant parameters such as energy levels, electron transport, exciton recombination or light outcoupling. Thermal evaporation offers control of the molecular orientation by changing the deposition temperature or the deposition rate. However, the deposition conditions are strongly linked to other properties of the glass such as density and thermal stability. The deposition conditions that yield optimal orientation may result in poorly stable and low-density glasses, detrimental for device performance. This work investigates the possibility of manipulating the molecular orientation of physical vapor-deposited glasses by applying external electric fields during the vapor deposition process. The goal is to align the permanent electric dipole moment of the molecules with the electric field lines. Three distinct organic semiconductor molecules are considered as glass formers: TPD and two brominated TPD derivatives: TPD-Br1 and TPD-Br2. The last two molecules were purposely created and synthesised for this study with the aim to increase the effect of the electric field, as they possess larger intrinsic dipole moments.