Contatto di riferimento: Laura Basiricò
Partecipanti: Marta Tessarolo: Istituto per lo Studio di Materiali Nanostrutturati (ISMN)
In the field of Organic Photovoltaics (OPVs) the solution processed Bulk Heterojunction (BHJ) solar cells have gained wide interest in past few years thanks to a constant enhancement of their Power Conversion Efficiency (PCE), that have reached 11%, joint to the main advantages of the organic electronics, such as low cost fabrication and compatibility with flexible and semitransparent substrates.
However, to be a competitive product, get high PCE is not enough, also the lifetime has to be improved. With a properly
encapsulation, the degradation mechanism due to oxygen and water can be neglected, but the high temperature (65°C-85°C) and the light soaking can induce processes that are detrimental for the solar cell.
To prevent them it is necessary a deeper understanding of the degradation mechanism occur into the BHJ solar cell. To do that we used the Impedance Spectroscopy (IS). This frequency resolved technique allows addressing dynamic operational electric mechanisms of OPV devices which are not detectable by standard steady-state J-V characteristics. For instance: charge separation, carrier transport (linked with series resistance), recombination losses or extraction efficiency (related to dynamic parallel resistance) and outer interface influences can be discerned. In this study we focus on the thermal degradation and we present the potentiality of the IS to investigate the thermal behavior of a BHJ solar cell.