Zombie - cells

Zombie-cells painted by Sigridur Huld Ingvarsdottir and reproduced from Energy & Environmental Science 2015, 8, 2634, with permission from the Royal Society of Chemistry

Referee comments are often read in an emotional state between hope and despair. But in rare occasions one gets happily surprised as in reading the word “breakthrough” as a comment from one of the referees to our work on Cu-complexes as a novel hole transporting material for solid-state dye-sensitized solar cells (ss-DSSC).

Our work on alternative redox couples for liquid type DSSC started at Uppsala University and Dr. Marina Freitag followed the promising works by Hattori and Peng Wang and their co-workers on Copper-phenanthroline complexes. Together with our coworkers at KTH, Stockholm, Marina’s investigations came with a big surprise! Having left some of the liquid sandwich solar cells with a Cu-phenanthroline electrolyte for some months with an unsuccessful sealing, the solvent of the electrolyte had evaporated and the cells had dried out. The cells were anyway tested and - lo and behold – the efficiencies of the dried cells were even higher compared to the initial liquid cells. Marina quickly coined the name ’Zombie cells’ for these dry and supposed-to-be dead cells. We reached the highest power conversion efficiency up to date for organic ss-DSSC of more than 8% efficiency, which was compared to the standard hole conductor spiro-OMeTAD with efficiencies between 5 and 6%.

Marina is now since July a post-doc in LSPM and in collaboration with for example Dr. Gerrit Boschloo’s group at Uppsala University we believe that these preliminary results open up new directions for integration of this new class of HTMs not only to ss-DSSCs or perovskite solar cells, but also in other areas of organic electronics, where the use of HTMs is essential.