
Photocurrent map for an organic solar cell made by ITO/PEDOT:PSS/P3HT-PCBM/Al using a homemade LBIC setup
Most members of the group are involved in PHOTOCOMB: Understanding and optimizing nanostructured organic photovoltaics through a processing scheme inspired by combinatorial analysis. This research program runs from 2013 to 2015 and it aims at developing processing schemes that enable the fabrication of organic photovoltaic (OPV) active layers with a controlled graded structure across its area in order to optimize device performance in an effective and speedy manner, as well as to allow fundamental studies on model samples. Inspired by the concept of combinatorial screening, we are studying samples showing continuous variations in one or two parameters, rather than using sets of discrete samples. The gradients span the following main parameters: degree of order, molecular orientation, composition and film thickness. We are implementing experimental setups to perform mapping characterization, in this way, the multiparameter space of the samples is systematically investigated to reveal the most relevant combination governing the performance of organic photovoltaics. During the project we will develop a characterization setup based on optimization for maximum photovoltaic efficiency by implementing an XYZ mapping stage with micrometer precision and a solar simulator to carry out photocurrent maps. We intend to demonstrate the different principles in the widely studied material system, polythiophene (P3HT) mixed with soluble derivative fullerene (PCBM) and then extend it to other systems with higher efficiencies. At the same time, establishing this interplay between fundamental knowledge and performance may help to identify spectroscopic probes that can be used to asses film quality during cell fabrication for in-situ monitoring at industrial level. Non-invasive methods such as ellipsometry and Raman show great potential for this, and the group has many years of experience on its application.





Sergi Riera receiving the grant awarded | Ajuntament de Barcelona









