"Fossil fuels consumption is no longer going to be substained both for its environmental impact and for the limited availability of such fuels. Solar energy produced from photovoltaic cells based on organic or organic/inorganic hybrid materials has been proposed as a sustainable alternative. By selectively chosing the electronic properties of two semiconducting polymers, and by mixing them in a polymer blend formed on solid substrate, well defined and efficient LEDs and photovoltaic diodes can be prepared. However, important issues like, the identification of the quantum-mechanical states involved in electron-hole recombination at the hetero-interface and the effect of intermolecular interactions on the optoelectronic response, have still to be investigated in detail. Most of these optoelectronic properties rely on the nature and distribution of the polymer heterojunctions in the blend therefore, the meso-scale structure determined by the kinetics of the phase separation process occurring during the blend formation, plays a crucial role on the devices performance. Our aim is to achieve a control over the molecular self-assembly, length scales and degree of self-organisation, of newly synthesized polyelectrolyte semiconductors and, correlate these features with their optoelectronic properties in LEDs and photovoltaic devices. Small Angle X-ray Scattering (SAXS) and Scanning Probe Microscopy (SPM) studies will allow us to determine the microscale and nanoscale structure of the blend, in terms of such parameters as particle sizes, shapes, distribution, and surface-to volume ratio. The present work will be developed in collaborations with researchers having a long time experience on making organic based optoelectronic devices and this will ensure that the output of the morphological study will be directely correlated to the device’s performance. This study will ultimately enable the optimization of these optoelectronic devices in terms of polymers interfacial mixing."