The organic semiconductor blend made of pBTTT:PCBM which is used in organic photovoltaics was studied in optical pump THz probe spectroscopy. The blend's composition is varied to introduce different local phase morphologies.
This study presents the electronic properties of charges within this organic semiconductor where we follow the ultrafast conductivity in these local phases over time and reveal how charges develop differently depending on the local phase they are in. On top of that we discuss how the different charge species govern the lifetime of charges within the system where we show that high local mobility leads to efficient charge separation but also significantly longer lifetimes.
This work was carried out in the group of Prof. Natalie Banerji.
P. Krauspe, D. Tsokkou, M. Causa', E. Buchaca-Domingo, Z. Fei, M. Heeney, N. Stingelin, N. Banerji;
"Terahertz short-range mobilities in neat and intermixed regions of polymer:fullerene blends with controlled phase morphology"
J. Mater. Chem. A, 2018, 6(44), 22301-22309;